[8.8.0] Fix enabling TCP keepalive on Linux.

[bazel-io]

Forked from #29902

[bazel-io]

Cherry-pick was attempted but there were merge conflicts in the following file(s). Please resolve manually.

src/main/java/com/google/devtools/build/lib/authandtls/GoogleAuthUtils.java

cc: @bazelbuild/triage

[iancha1992]

@fmeum @coeuvre
I cannot cherry-pick 46c5e78 unless I also cherry-pick 47b0fd6. Is this okay?

[fmeum]

Yes, that's an expected prerequisite. Thanks!

[iancha1992]

Cherry-picked in #29968