Unable to generate client libraries in the `google.api` namespace

[parthea]

We're unable to generate client libraries in the google.api namespace because the namespace is already owned by googleapis-common-protos : https://github.com/googleapis/python-api-common-protos/tree/main/google/api

There is a workaround, which is to generate the client library in the in the google.cloud namespace instead of google.api if it is also a Cloud API. For example, for google.api.apikeys, we have a client library `google-cloud-api-keys. https://github.com/googleapis/googleapis/blob/master/google/api/apikeys https://github.com/googleapis/google-cloud-python/tree/main/packages/google-cloud-api-keys

It would be a breaking change to drop googleapis-common-protos but doing so would allow us to avoid a conflict in the google.api namespace.

This is possibly related to https://github.com/googleapis/gapic-generator-python/issues/1850 which is to include protobuf dependencies as part of the library.