Fix angular distance calculation in floating joint model (backport #2538)

[mergify]

This is an automatic backport of pull request #2538 done by Mergify.
Cherry-pick of 83ff55a has failed:

On branch mergify/bp/iron/pr-2538
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Changes to be committed:
	modified:   moveit_core/robot_model/src/floating_joint_model.cpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   moveit_core/robot_trajectory/test/test_robot_trajectory.cpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (2ee72ae) 50.74% compared to head (5a690f8) 50.71%.

Additional details and impacted files

@@            Coverage Diff             @@
##             iron    #2544      +/-   ##
==========================================
- Coverage   50.74%   50.71%   -0.03%     
==========================================
  Files         386      385       -1     
  Lines       31982    31980       -2     
==========================================
- Hits        16227    16215      -12     
- Misses      15755    15765      +10     

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