[test] protobuf 3.25.5 for testing with 6.66.x

[zhumin8]

test for lts 7 patch.

[conventional-commit-lint-gcf]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot
https://conventionalcommits.org/

[zhumin8]

kokoro integration test failure:

[ERROR] Failures: 
[ERROR]   CloseSpannerWithOpenResultSetTest.testBatchClient_closedSpannerWithOpenResultSet_streamsAreCancelled:99 expected com.google.cloud.spanner.SpannerException to be thrown, but nothing was thrown

[zhumin8]

Test failure resolved in rerun.
passed it and unit tests.