Fix: Resolve race condition in MoveGroupSequenceAction (backport #3125)

[mergify]

Description

Replaced ReentrantCallbackGroup with MutuallyExclusiveCallbackGroup in MoveGroupSequenceAction::initialize to prevent race conditions during stress testing.

This change ensures sequential execution of callbacks, avoiding issues caused by concurrent execution.

Reference: #3117

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

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This is an automatic backport of pull request #3125 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 6d94dfb has failed:

On branch mergify/bp/humble/pr-3125
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Unmerged paths:
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	both modified:   moveit_planners/pilz_industrial_motion_planner/src/move_group_sequence_action.cpp

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[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 42.28%. Comparing base (92e8808) to head (e1b218b).
Report is 1 commits behind head on humble.

Files with missing lines	Patch %	Lines
..._motion_planner/src/move_group_sequence_action.cpp	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##           humble    #3127      +/-   ##
==========================================
+ Coverage   42.26%   42.28%   +0.03%     
==========================================
  Files         668      668              
  Lines       57741    57742       +1     
  Branches     7322     7323       +1     
==========================================
+ Hits        24396    24410      +14     
+ Misses      33159    33147      -12     
+ Partials      186      185       -1     

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