[tests] Improve handling of nodes and plugins registration in unit tests

[cbentejac]

Description

This PR improves the reliability and isolation of tests involving plugin and node registration by ensuring that all registered node descriptions and plugins are properly unregistered or removed after each test or test class. This helps prevent side effects between tests and makes the test suite more robust.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.03%. Comparing base (a23a09d) to head (83c64b3).
⚠️ Report is 9 commits behind head on develop.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2999      +/-   ##
===========================================
+ Coverage    82.01%   82.03%   +0.01%     
===========================================
  Files           69       69              
  Lines         9310     9318       +8     
===========================================
+ Hits          7636     7644       +8     
  Misses        1674     1674              

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