Fix bullet related segfaults on macOS

[azeey]

🦟 Bug fix

Fixes #497

Summary

This fixes two tests with segfaults on macOS

1. COMMON_TEST_simulation_features_bullet-featherstone: The failure appears to be due to the destruction order of the triangleMeshes and meshesGImpact containers. Per [this] (Should btBroadphaseInterface destructor remove itself from btCollisionObject broadphase proxies?  bulletphysics/bullet3#567 (comment)) comment, memory in bullet is sensitive to order of destruction. meshesGImpact objects contain pointers to items contained bytriangleMeshes, so the solution is to ensure meshesGImpact is destructed before triangleMeshes.
2. INTEGRATION_DoublePendulum: This is a DART test, but the segfault seems to be related to Bullet. I found that even after removing all the code in DARTDoublePendulum.cc, the segfault still occurs as long as it's linked with libdart-collision-bullet. Since the test doesn't need the bullet collision detector, I've opted to just remove the library from the DART_LIBRARIES variable. I still don't know the root cause though, so this might affect the actual dartsim-plugin library.

Checklist

• Signed all commits for DCO
• Added 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

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[codecov]

Codecov Report

Merging #504 (03f93c7) into gz-physics6 (12baaf7) will not change coverage.
The diff coverage is n/a.

❗ Current head 03f93c7 differs from pull request most recent head f2b1d36. Consider uploading reports for the commit f2b1d36 to get more accurate results

@@             Coverage Diff              @@
##           gz-physics6     #504   +/-   ##
============================================
  Coverage        75.50%   75.50%           
============================================
  Files              142      142           
  Lines             7173     7173           
============================================
  Hits              5416     5416           
  Misses            1757     1757           

Impacted Files	Coverage Δ
bullet-featherstone/src/Base.hh	100.00% <ø> (ø)

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[azeey]

The windows warnings are coming from gz-math and I believe are fixed by gazebosim/gz-math#529