chore(all): auto-regenerate .pb.go files (googleapis#521)

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#3607

Changes:

docs: test cases doc update
  PiperOrigin-RevId: 353683381
  Source-Link: googleapis/googleapis@2e29020

fix(datacatalog): Update PHP package name casing to match the PHP namespace in the proto files
  PiperOrigin-RevId: 353287430
  Source-Link: googleapis/googleapis@43655b7

feat(spanner): add option for returning Spanner commit stats
  PiperOrigin-RevId: 353145174
  Source-Link: googleapis/googleapis@8fa381b

regen.txt

@@ -1 +1 @@
-8fa381b7138f1d72966ff20563efae1b2194d359
+2e29020ce87808b810deb20e0925b7e26c5e72c1