Disable MacOS flakies Citadel

[Blast545]

Backport of #1398 to Citadel and temporary disabled tests for #630 #154

Summary

Disabling flaky tests on MacOS to help with gazebo-tooling/release-tools#398

Checklist

• Signed all commits for DCO
• Added tests -> actually disabling tests
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

[chapulina]

I'll leave a cross-link to #807, which I believe intended to fix these tests. CC @azeey

[codecov]

Codecov Report

Merging #1545 (58514b6) into ign-gazebo3 (dc5f117) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff              @@
##           ign-gazebo3    #1545   +/-   ##
============================================
  Coverage        77.76%   77.76%           
============================================
  Files              250      250           
  Lines            14443    14443           
============================================
  Hits             11231    11231           
  Misses            3212     3212           

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[Blast545]

All tests passing, want to review and merge? :D @chapulina

Besides the remaining protobuf warnings, I think Citadel is all covered to enable CI checks. I'll move further with Fortress now.

[chapulina]

Thanks, @Blast545 , let's give this a try for a few weeks and see if other flakies come up.