Add more parameter overriding tests from parsing multiple parameter files

[saikishor]

This PR just adds more tests to test the parameter overriding concepts more explicitly

[codecov]

Codecov Report

Attention: Patch coverage is 82.50000% with 7 lines in your changes missing coverage. Please review.

Project coverage is 87.83%. Comparing base (c9a0ab9) to head (900bfb2).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
controller_manager/test/test_spawner_unspawner.cpp	82.50%	0 Missing and 7 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1899      +/-   ##
==========================================
- Coverage   87.85%   87.83%   -0.02%     
==========================================
  Files         121      121              
  Lines       12515    12555      +40     
  Branches     1124     1131       +7     
==========================================
+ Hits        10995    11028      +33     
  Misses       1108     1108              
- Partials      412      419       +7     

Flag	Coverage Δ
unittests	87.83% <82.50%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
controller_manager/test/test_spawner_unspawner.cpp	97.31% <82.50%> (-1.79%)	⬇️

[christophfroehlich]

LGTM. Unfortunately, the coverage metrics don't acknowledge your efforts :(

[saikishor]

LGTM. Unfortunately, the coverage metrics don't acknowledge your efforts :(

Hahahhaa It happens XD