rqt_cm: Robustify test and fix shutdown races (backport #3396)

[mergify]

Description

Fixes several shutdown races

Closes ros-controls/ros2_control_ci#840, closes ros-controls/ros2_control_ci#841, closes ros-controls/ros2_control_ci#842, closes ros-controls/ros2_control_ci#843, closes ros-controls/ros2_control_ci#844 closes ros-controls/ros2_control_ci#847 closes ros-controls/ros2_control_ci#846

Is this user-facing behavior change?

no

Did you use Generative AI?

GPT-5.3-Codex

---

This is an automatic backport of pull request #3396 done by Mergify.

[mergify]

Cherry-pick of 427cb38 has failed:

On branch mergify/bp/jazzy/pr-3396
Your branch is up to date with 'origin/jazzy'.

You are currently cherry-picking commit 427cb38.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   rqt_controller_manager/rqt_controller_manager/controller_manager.py

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   rqt_controller_manager/test/test_run_launch.py

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

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.51%. Comparing base (6dbcd10) to head (0082288).

Additional details and impacted files

@@           Coverage Diff           @@
##            jazzy    #3464   +/-   ##
=======================================
  Coverage   89.51%   89.51%           
=======================================
  Files         163      163           
  Lines       20651    20651           
  Branches     1633     1633           
=======================================
  Hits        18485    18485           
  Misses       1494     1494           
  Partials      672      672           

Flag	Coverage Δ
unittests	89.51% <ø> (ø)

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