chore: Update discovery artifacts (#1486)

## Deleted keys were detected in the following stable discovery artifacts:
displayvideo v1 https://github.com/googleapis/google-api-python-client/commit/21f81c824089d0060dbd624f9755eea554464af2
sts v1 https://github.com/googleapis/google-api-python-client/commit/a8ebc2bef5d0ff6c449d65fcc9c0554c1f388985

## Deleted keys were detected in the following pre-stable discovery artifacts:
networkconnectivity v1alpha1 https://github.com/googleapis/google-api-python-client/commit/68588ad4744aa3c7a3a0afa12a1566f54ab3be94

## Discovery Artifact Change Summary:
feat(apigee): update the api https://github.com/googleapis/google-api-python-client/commit/41ae79b3554ffc9f1622e44757751009eeed76f8
feat(bigqueryreservation): update the api https://github.com/googleapis/google-api-python-client/commit/b0483aba20b17580b400283fb0073f07715bf254
feat(chat): update the api https://github.com/googleapis/google-api-python-client/commit/270312294f1cf89041825b0f31bfcf872fda9854
feat(cloudbuild): update the api https://github.com/googleapis/google-api-python-client/commit/30c122278e75a99b5b2a6ed330f317015134a23d
feat(cloudscheduler): update the api https://github.com/googleapis/google-api-python-client/commit/0405b1db79fe87305be25ba4f9389e94490040a7
feat(contactcenterinsights): update the api https://github.com/googleapis/google-api-python-client/commit/3abcf5334053f5612fd79163f2c433e5793ee782
feat(dialogflow): update the api https://github.com/googleapis/google-api-python-client/commit/c4935840495b1487d4be47b63f6c416113b9413f
feat(displayvideo): update the api https://github.com/googleapis/google-api-python-client/commit/21f81c824089d0060dbd624f9755eea554464af2
feat(monitoring): update the api https://github.com/googleapis/google-api-python-client/commit/d997b2c0d13203ac29b55c19858ef375380a5b7b
feat(networkconnectivity): update the api https://github.com/googleapis/google-api-python-client/commit/68588ad4744aa3c7a3a0afa12a1566f54ab3be94
feat(notebooks): update the api https://github.com/googleapis/google-api-python-client/commit/b975c34568f62bbf19f67f4731fe091aeeda8a75
feat(retail): update the api https://github.com/googleapis/google-api-python-client/commit/c2bcb7081a4f656b9e136ea38637cf262b60f387
feat(servicenetworking): update the api https://github.com/googleapis/google-api-python-client/commit/3bdc7b9d0854918ef65ccb4a3798d2f3f3b19d70
feat(sts): update the api https://github.com/googleapis/google-api-python-client/commit/a8ebc2bef5d0ff6c449d65fcc9c0554c1f388985
diff --git a/googleapiclient/discovery_cache/documents/adexchangebuyer.v1.3.json b/googleapiclient/discovery_cache/documents/adexchangebuyer.v1.3.json
index 2205513..ce0014b 100644
--- a/googleapiclient/discovery_cache/documents/adexchangebuyer.v1.3.json
+++ b/googleapiclient/discovery_cache/documents/adexchangebuyer.v1.3.json
@@ -15,7 +15,7 @@
   "description": "Accesses your bidding-account information, submits creatives for validation, finds available direct deals, and retrieves performance reports.",
   "discoveryVersion": "v1",
   "documentationLink": "https://developers.google.com/ad-exchange/buyer-rest",
-  "etag": "\"uWj2hSb4GVjzdDlAnRd2gbM1ZQ8/b-tin2Zp8AUX8vgd4BCYL_nvJSQ\"",
+  "etag": "\"uWj2hSb4GVjzdDlAnRd2gbM1ZQ8/NOgo5Rz2N67ZT2NXIcz-dCGvAbI\"",
   "icons": {
     "x16": "https://www.google.com/images/icons/product/doubleclick-16.gif",
     "x32": "https://www.google.com/images/icons/product/doubleclick-32.gif"
@@ -699,7 +699,7 @@
       }
     }
   },
-  "revision": "20210808",
+  "revision": "20210815",
   "rootUrl": "https://www.googleapis.com/",
   "schemas": {
     "Account": {