This PR's commits were extracted from #6273 where I'm working on getting pants+pytest to run integration tests.

This PR primarily makes this change, plus a few other minor things:

• BUILD metadata for integration tests, including explicit dependencies that could not be inferred and uses= config for our pants-plugins/uses_services plugin.

The other minor things I included are:

• Silence pants' remote cache warnings. GitHub Actions Caching has a really low API rate limit that we hit regularly. When we hit that, we get 429 errors that pants displays as warnings (LOTS of warnings). The warnings are not actionable--we can't do anything about GitHub's paltry rate limit--and there is basically no impact on our CI--pants just runs the process if it can't find it in the cache or the cache returns an error. All of those warnings were obscuring the actual test output, so this silences them.
• I couldn't run some tests locally because they require passwordless sudo, which I don't want to configure. So, I skipped those tests, leaving them to run only in CI.
• Add a generous timeout for pants to run each test file. I set [test].timeout_default=600 (ie 10min in seconds) so that pants doesn't hang running integration tests if something goes wrong. If a test times out, pants will just retry it up to 3 times, so this just serves to speed up CI when we run into edge cases.