[Test] add explicit marker for trailing whitespace in cases

[G-Rath]

This ensures that IDEs like Webstorm won't trim trailing whitespace that is expected as part of test output

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.30%. Comparing base (038c26c) to head (8bdb32b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3045      +/-   ##
==========================================
+ Coverage   95.19%   95.30%   +0.11%     
==========================================
  Files          81       81              
  Lines        3411     3411              
  Branches     1195     1195              
==========================================
+ Hits         3247     3251       +4     
+ Misses        164      160       -4     

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[ljharb]

Thanks! this is good test case hygiene anyways :-)