chore(test): add version check for forward compat test

[skyzh]

Problem

A test for #7684.

This pull request checks if the pageserver version we specified is the one actually running by comparing the git hash in forward compatibility tests.

Summary of changes

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

3060 tests run: 2927 passed, 0 failed, 133 skipped (full report)

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Code coverage* (full report)

• functions: 31.4% (6333 of 20168 functions)
• lines: 47.3% (47832 of 101111 lines)

* collected from Rust tests only

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_{The comment gets automatically updated with the latest test results
2bbe2c8 at 2024-05-13T17:07:04.502Z :recycle:}

[skyzh]

main branch fails as expected:

2024-05-09T19:48:30.9828603Z FAILED test_runner/regress/test_compatibility.py::test_forward_compatibility[release-pg14]@compatibility - AssertionError: assert None
2024-05-09T19:48:30.9829128Z  +  where None = <bound method LogUtils.log_contains of <fixtures.neon_fixtures.NeonPageserver object at 0x7f4807226a00>>(('git-env:' + 'c4d7d5982553d2cf66634d1fbf85d95ef44a6524'))

https://github.com/neondatabase/neon/actions/runs/9022433795/job/24792429931

[skyzh]

Ideally, we should also check Postgres version, but I don't think the compute node is printing git rev. And also due to a bug of how CI handles pg_distrib_dir, we are not using the correct Postgres version for forward compat test now.

[skyzh]

https://github.com/neondatabase/neon/pull/7684/files#diff-9ffba544d49919e927a416b899e92d769f37f3c8355258eb212678b4e5ca067bR704-R705

#7741

[problame]

Approving with the reservation to please add the requested assertion