Backport #7917, #7974 and #7975 to release-12.1

[onurctirtir]

cherry-pick the following at once for citus_stat_counters, not just the first commit:

3d61c4dc71ef5f2377139662694746ace06216b2 d2e6cf1de0072ca012f27bce974dcfa95f16696b ea7aa6712dc8135b0aadd53943adcbbc4b63dd5b

This only backports binary changes and the tests for testing early on dev machines. For tests to work, also defines the user-facing UDFs for related test files.

DESCRIPTION: PR description that will go into the change log, up to 78 characters

[codecov[bot]]

Codecov Report

:x: Patch coverage is 84.69388% with 45 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 84.80%. Comparing base (cb31a64) to head (d2cf3f0). :warning: Report is 27 commits behind head on release-12.1.

:x: Your project check has failed because the head coverage (84.80%) is below the target coverage (87.50%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@               Coverage Diff                @@
##           release-12.1    #8208      +/-   ##
================================================
- Coverage         89.57%   84.80%   -4.78%     
================================================
  Files               276      277       +1     
  Lines             59660    60009     +349     
  Branches           7448     7509      +61     
================================================
- Hits              53442    50891    -2551     
- Misses             4081     6477    +2396     
- Partials           2137     2641     +504     

:rocket: New features to boost your workflow:

• :snowflake: Test Analytics: Detect flaky tests, report on failures, and find test suite problems.