chore: Update discovery artifacts (#1400)

## Discovery Artifact Change Summary:
feat(compute): update the api https://github.com/googleapis/google-api-python-client/commit/b8ce2754752f8157b84091a99594f9a45a8f8eed
feat(container): update the api https://github.com/googleapis/google-api-python-client/commit/a73f41e49d7ab6258bd722b4ee6d022c195975c2
feat(dataproc): update the api https://github.com/googleapis/google-api-python-client/commit/be0dde6ee43f4ff05396d33b16e0af2a1fabfc28
feat(lifesciences): update the api https://github.com/googleapis/google-api-python-client/commit/c524c0a316e4206c8b0e0075e3ed5eceb7e60016
feat(osconfig): update the api https://github.com/googleapis/google-api-python-client/commit/5dbaaad34dec45eb5f5a9e98710b3ec05b4d5429
feat(pagespeedonline): update the api https://github.com/googleapis/google-api-python-client/commit/47d41c544376b1911261410235b63ffe3e5faa91
feat(privateca): update the api https://github.com/googleapis/google-api-python-client/commit/8f7ad0d176d61f9e9a409d7fe35b20c5f1c239a5
diff --git a/googleapiclient/discovery_cache/documents/container.v1beta1.json b/googleapiclient/discovery_cache/documents/container.v1beta1.json
index d632332..9924353 100644
--- a/googleapiclient/discovery_cache/documents/container.v1beta1.json
+++ b/googleapiclient/discovery_cache/documents/container.v1beta1.json
@@ -2484,7 +2484,7 @@
       }
     }
   },
-  "revision": "20210517",
+  "revision": "20210521",
   "rootUrl": "https://container.googleapis.com/",
   "schemas": {
     "AcceleratorConfig": {
@@ -2612,6 +2612,10 @@
           "description": "Type of the disk attached to each node (e.g. 'pd-standard', 'pd-ssd' or 'pd-balanced') If unspecified, the default disk type is 'pd-standard'",
           "type": "string"
         },
+        "imageType": {
+          "description": "The image type to use for NAP created node.",
+          "type": "string"
+        },
         "management": {
           "$ref": "NodeManagement",
           "description": "NodeManagement configuration for this NodePool."
@@ -4400,7 +4404,7 @@
       "type": "object"
     },
     "NodePool": {
-      "description": "NodePool contains the name and configuration for a cluster's node pool. Node pools are a set of nodes (i.e. VM's), with a common configuration and specification, under the control of the cluster master. They may have a set of Kubernetes labels applied to them, which may be used to reference them during pod scheduling. They may also be resized up or down, to accommodate the workload.",
+      "description": "NodePool contains the name and configuration for a cluster's node pool. Node pools are a set of nodes (i.e. VM's), with a common configuration and specification, under the control of the cluster master. They may have a set of Kubernetes labels applied to them, which may be used to reference them during pod scheduling. They may also be resized up or down, to accommodate the workload. These upgrade settings control the level of parallelism and the level of disruption caused by an upgrade. maxUnavailable controls the number of nodes that can be simultaneously unavailable. maxSurge controls the number of additional nodes that can be added to the node pool temporarily for the time of the upgrade to increase the number of available nodes. (maxUnavailable + maxSurge) determines the level of parallelism (how many nodes are being upgraded at the same time). Note: upgrades inevitably introduce some disruption since workloads need to be moved from old nodes to new, upgraded ones. Even if maxUnavailable=0, this holds true. (Disruption stays within the limits of PodDisruptionBudget, if it is configured.) Consider a hypothetical node pool with 5 nodes having maxSurge=2, maxUnavailable=1. This means the upgrade process upgrades 3 nodes simultaneously. It creates 2 additional (upgraded) nodes, then it brings down 3 old (not yet upgraded) nodes at the same time. This ensures that there are always at least 4 nodes available.",
       "id": "NodePool",
       "properties": {
         "autoscaling": {
@@ -5840,7 +5844,6 @@
       "type": "object"
     },
     "UpgradeSettings": {
-      "description": "These upgrade settings control the level of parallelism and the level of disruption caused by an upgrade. maxUnavailable controls the number of nodes that can be simultaneously unavailable. maxSurge controls the number of additional nodes that can be added to the node pool temporarily for the time of the upgrade to increase the number of available nodes. (maxUnavailable + maxSurge) determines the level of parallelism (how many nodes are being upgraded at the same time). Note: upgrades inevitably introduce some disruption since workloads need to be moved from old nodes to new, upgraded ones. Even if maxUnavailable=0, this holds true. (Disruption stays within the limits of PodDisruptionBudget, if it is configured.) Consider a hypothetical node pool with 5 nodes having maxSurge=2, maxUnavailable=1. This means the upgrade process upgrades 3 nodes simultaneously. It creates 2 additional (upgraded) nodes, then it brings down 3 old (not yet upgraded) nodes at the same time. This ensures that there are always at least 4 nodes available.",
       "id": "UpgradeSettings",
       "properties": {
         "maxSurge": {