Fix controller activation crash on macOS (Fixes #604) (backport #2391)

[mergify]

This PR resolves #604, which caused a runtime crash on macOS during controller activation.

The issue stemmed from the use of std::defer_lock with std::unique_lock prior to calling wait() on a condition variable. On macOS, the underlying libc++ implementation strictly enforces that a mutex must be locked before invoking wait(). Since defer_lock does not acquire the lock, this led to undefined behavior and a crash at runtime.

This PR corrects the locking behavior by ensuring the mutex is properly locked before wait() is called, making the code safe and portable across platforms, including macOS.

---

This is an automatic backport of pull request #2391 done by Mergify.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.65%. Comparing base (a34ef90) to head (1e05d51).
Report is 1 commits behind head on jazzy.

Additional details and impacted files

@@            Coverage Diff             @@
##            jazzy    #2396      +/-   ##
==========================================
- Coverage   88.69%   88.65%   -0.04%     
==========================================
  Files         145      145              
  Lines       16747    16747              
  Branches     1444     1444              
==========================================
- Hits        14853    14847       -6     
- Misses       1333     1339       +6     
  Partials      561      561              

Flag	Coverage Δ
unittests	88.65% <100.00%> (-0.04%)	⬇️

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Files with missing lines	Coverage Δ
controller_manager/src/controller_manager.cpp	74.53% <100.00%> (ø)

... and 3 files with indirect coverage changes

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