chore: Update discovery artifacts (#1450)

## Deleted keys were detected in the following stable discovery artifacts:
chat v1 https://github.com/googleapis/google-api-python-client/commit/8e39e1ef5482735fbaaed3be74ee472cf44cd941
dns v1 https://github.com/googleapis/google-api-python-client/commit/e2ba913fc51f78ce4b9fb6f9de97f61bd35cd356

## Deleted keys were detected in the following pre-stable discovery artifacts:
dns v1beta2 https://github.com/googleapis/google-api-python-client/commit/e2ba913fc51f78ce4b9fb6f9de97f61bd35cd356

## Discovery Artifact Change Summary:
feat(analyticsadmin): update the api https://github.com/googleapis/google-api-python-client/commit/a2e2d768e5412072ef11891ae7fb9145e2c4693d
feat(androiddeviceprovisioning): update the api https://github.com/googleapis/google-api-python-client/commit/83151f4ebd2992a53f815133304d8cb2c72d50c5
feat(chat): update the api https://github.com/googleapis/google-api-python-client/commit/8e39e1ef5482735fbaaed3be74ee472cf44cd941
feat(cloudasset): update the api https://github.com/googleapis/google-api-python-client/commit/ebd9b97ec74f0f257ccb4833f747f88d02075926
feat(cloudfunctions): update the api https://github.com/googleapis/google-api-python-client/commit/06332af99b1b1a9894bf4f553e014936225761de
feat(cloudsearch): update the api https://github.com/googleapis/google-api-python-client/commit/4aab6137bb350cb841a6b48fd37df67a209ba031
feat(content): update the api https://github.com/googleapis/google-api-python-client/commit/c65f297a775687fbfcbae827f892fc996a3d1ab1
feat(datacatalog): update the api https://github.com/googleapis/google-api-python-client/commit/af28eef0b37a5d0bb3a299f9fd9740b63f9e23bd
feat(dns): update the api https://github.com/googleapis/google-api-python-client/commit/e2ba913fc51f78ce4b9fb6f9de97f61bd35cd356
feat(documentai): update the api https://github.com/googleapis/google-api-python-client/commit/d1b9df7ee0a041d4cf632a77a626764c37e72889
feat(file): update the api https://github.com/googleapis/google-api-python-client/commit/0cd6277980d02363e3d609901d12d62b594adc92
feat(firebaseappcheck): update the api https://github.com/googleapis/google-api-python-client/commit/f8c39017aa392c0930ab79cdf7f828fe1e97e313
feat(firebasestorage): update the api https://github.com/googleapis/google-api-python-client/commit/66b6961871fea5b1a41a5b8359d7f76d6e390386
feat(gameservices): update the api https://github.com/googleapis/google-api-python-client/commit/31fd4dc22bd1e615caeafc22482caad65bbd55e9
feat(gkehub): update the api https://github.com/googleapis/google-api-python-client/commit/58ae34d8dfb4a7827b4f56e99fd48dedc64b4364
feat(ml): update the api https://github.com/googleapis/google-api-python-client/commit/15e0de32f2ea94d6ed3e0c18cd6e59cc239b37e7
feat(monitoring): update the api https://github.com/googleapis/google-api-python-client/commit/2b52d9ff5341caec20577538c0c4eaf83a896651
feat(notebooks): update the api https://github.com/googleapis/google-api-python-client/commit/c4698a84e526ab47710d2bde22827b337f2f480c
feat(people): update the api https://github.com/googleapis/google-api-python-client/commit/a646e56d40f2c7df40f48d42442c1941fc1c6674
feat(recommender): update the api https://github.com/googleapis/google-api-python-client/commit/ef997b0293c0e075208c7af15fa4e9bd6f29e883
feat(secretmanager): update the api https://github.com/googleapis/google-api-python-client/commit/489541e760eae9745724eb8cad74007903dd4f5b
feat(spanner): update the api https://github.com/googleapis/google-api-python-client/commit/acdb8fccfbb9f243f06dfff68d61cee2e58c9e45
feat(testing): update the api https://github.com/googleapis/google-api-python-client/commit/e2bde192a3e20ebd00995185cd92b47a086be8d9
diff --git a/googleapiclient/discovery_cache/documents/networksecurity.v1beta1.json b/googleapiclient/discovery_cache/documents/networksecurity.v1beta1.json
index 0ddd35c..1430c85 100644
--- a/googleapiclient/discovery_cache/documents/networksecurity.v1beta1.json
+++ b/googleapiclient/discovery_cache/documents/networksecurity.v1beta1.json
@@ -1037,7 +1037,7 @@
       }
     }
   },
-  "revision": "20210624",
+  "revision": "20210709",
   "rootUrl": "https://networksecurity.googleapis.com/",
   "schemas": {
     "AuthorizationPolicy": {
@@ -1538,7 +1538,7 @@
       "id": "MTLSPolicy",
       "properties": {
         "clientValidationCa": {
-          "description": "Required. Defines the mechanism to obtain the Certificate Authority certificate to validate the client certificate.",
+          "description": " Defines the mechanism to obtain the Certificate Authority certificate to validate the client certificate.",
           "items": {
             "$ref": "ValidationCA"
           },
@@ -1648,11 +1648,11 @@
       "type": "object"
     },
     "ServerTlsPolicy": {
-      "description": "ServerTlsPolicy is a resource that specifies how a server should authenticate incoming requests. This resource itself does not affect configuration unless it is attached to a target https proxy or endpoint config selector resource.",
+      "description": "ServerTlsPolicy is a resource that specifies how a server should authenticate incoming requests. This resource itself does not affect configuration unless it is attached to a target https proxy or endpoint config selector resource. ",
       "id": "ServerTlsPolicy",
       "properties": {
         "allowOpen": {
-          "description": "Optional. Determines if server allows plaintext connections. If set to true, server allows plain text connections. By default, it is set to false. This setting is not exclusive of other encryption modes. For example, if allow_open and mtls_policy are set, server allows both plain text and mTLS connections. See documentation of other encryption modes to confirm compatibility.",
+          "description": " Determines if server allows plaintext connections. If set to true, server allows plain text connections. By default, it is set to false. This setting is not exclusive of other encryption modes. For example, if `allow_open` and `mtls_policy` are set, server allows both plain text and mTLS connections. See documentation of other encryption modes to confirm compatibility.",
           "type": "boolean"
         },
         "createTime": {
@@ -1662,19 +1662,19 @@
           "type": "string"
         },
         "description": {
-          "description": "Optional. Free-text description of the resource.",
+          "description": "Free-text description of the resource.",
           "type": "string"
         },
         "labels": {
           "additionalProperties": {
             "type": "string"
           },
-          "description": "Optional. Set of label tags associated with the resource.",
+          "description": "Set of label tags associated with the resource.",
           "type": "object"
         },
         "mtlsPolicy": {
           "$ref": "MTLSPolicy",
-          "description": "Optional. Defines a mechanism to provision peer validation certificates for peer to peer authentication (Mutual TLS - mTLS). If not specified, client certificate will not be requested. The connection is treated as TLS and not mTLS. If allow_open and mtls_policy are set, server allows both plain text and mTLS connections."
+          "description": " Defines a mechanism to provision peer validation certificates for peer to peer authentication (Mutual TLS - mTLS). If not specified, client certificate will not be requested. The connection is treated as TLS and not mTLS. If `allow_open` and `mtls_policy` are set, server allows both plain text and mTLS connections."
         },
         "name": {
           "description": "Required. Name of the ServerTlsPolicy resource. It matches the pattern `projects/*/locations/{location}/serverTlsPolicies/{server_tls_policy}`",
@@ -1682,7 +1682,7 @@
         },
         "serverCertificate": {
           "$ref": "GoogleCloudNetworksecurityV1beta1CertificateProvider",
-          "description": "Optional. Defines a mechanism to provision server identity (public and private keys). Cannot be combined with allow_open as a permissive mode that allows both plain text and TLS is not supported."
+          "description": " Defines a mechanism to provision server identity (public and private keys). Cannot be combined with `allow_open` as a permissive mode that allows both plain text and TLS is not supported."
         },
         "updateTime": {
           "description": "Output only. The timestamp when the resource was updated.",