chore(all): auto-regenerate .pb.go files (googleapis#767)

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#5705

Changes:

chore: disable Python snippetgen for bigtable
  PiperOrigin-RevId: 431126635
  Source-Link: googleapis/googleapis@dbfbfdb

chore: update copyright year to 2022
  PiperOrigin-RevId: 431037888
  Source-Link: googleapis/googleapis@b3397f5

docs(dialogflow/cx): updated copyright
  PiperOrigin-RevId: 431035391
  Source-Link: googleapis/googleapis@4b39bf1

chore: add outer class name for CVSS.proto
  PiperOrigin-RevId: 430998475
  Source-Link: googleapis/googleapis@19753e2

chore: regenerate API index

  Source-Link: googleapis/googleapis@5c4db90

feat(dialogflow): added ConversationModel resource and its APIs feat: added ConversationDataset resource and its APIs feat: added SetSuggestionFeatureConfig and ClearSuggestionFeatureConfig APIs for ConversationProfile feat: added new knowledge type of Document content feat: added states of Document feat: added metadata for the Knowledge operation docs: updated copyright
  PiperOrigin-RevId: 430829291
  Source-Link: googleapis/googleapis@83795dd

build(spanner): add flag to distinguish autogenerated libs with a handwritten layer
  PiperOrigin-RevId: 430741048
  Source-Link: googleapis/googleapis@6bd2087