feat(all): auto-regenerate .pb.go files (#512)

This is an auto-generated regeneration of the .pb.go files by
cloud.google.com/go/internal/gapicgen. Once this PR is submitted, genbot will
update the corresponding PR to depend on the newer version of go-genproto, and
assign reviewers. Whilst this or any regen PR is open in go-genproto, genbot
will not create any more regeneration PRs. If all regen PRs are closed,
gapicgen will create a new set of regeneration PRs once per night.

If you have been assigned to review this PR, please:

- Ensure that CI is passing. If it's failing, it requires your manual attention.
- Approve and submit this PR if you believe it's ready to ship. That will prompt
genbot to assign reviewers to the google-cloud-go PR.

Corresponding google-cloud-go PR: googleapis/google-cloud-go#3514

Changes:
- feat: Added OAuth scope for the service

  PiperOrigin-RevId: 350670798
  Source-Link: googleapis/googleapis@b241bbc

- chore: remove CircleCI configuration (#637)

  We have this repo covered by Kokoro CI.
  Source-Link: googleapis/googleapis@e843bea

- feat: IntroduceMembership API v1alpha2 proto

  PiperOrigin-RevId: 350654259
  Source-Link: googleapis/googleapis@68122a0

- chore(bigquery/reservation): use python microgenerator rules for Cloud APIs

  PiperOrigin-RevId: 350604597
  Source-Link: googleapis/googleapis@3131ab5

- chore: update gapic-generator ruby to latest version

  PiperOrigin-RevId: 350595874
  Source-Link: googleapis/googleapis@1d5300e

- chore: update gapic-generator-go to v0.17.0

  Changes include:
  - a default audience is generated for client JWT creation
  - treats RPCs that have some pagination fields but no repeated field as normal RPCs
  - use DefaultEndpoint and DefaultMTLSEndpoint for default options
  - updates to bazel & Go deps

  PiperOrigin-RevId: 350447881
  Source-Link: googleapis/googleapis@5a3edc8

- chore(analytics/admin): put markdown table in a codeblock

  PiperOrigin-RevId: 350414815
  Source-Link: googleapis/googleapis@700afd1

- chore(cloudbuild/apiv1): Update C# namespace

  This is a breaking change, but *only* for C#. Google has not yet published a package for this API, so it would only break users who have generated the code themselves.

  PiperOrigin-RevId: 350388717
  Source-Link: googleapis/googleapis@dd1d232

- chore: upgrade gapic-generator-python to 0.39.1

  feat: add 'from_service_account_info' factory to clients
  fix: fix sphinx identifiers
  PiperOrigin-RevId: 350246057
  Source-Link: googleapis/googleapis@5206824

- feat: Add ProvisionCloudIdentity API definitions for Cloud Channel API. Update documentation for other APIs.

  PiperOrigin-RevId: 350209421
  Source-Link: googleapis/googleapis@781d34e