test: Force terminate helper processes still running at dispose time

[chynesNR]

An intermittent integration test failure I've noticed: if a RemoteProcess is hung, we can still send it shutdown signals without getting an error back, so we never force it to close. Then when we make our final attempt to shut it down in Dispose, it throws because the test logger is no longer available.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.40%. Comparing base (2460527) to head (ecf0a03).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2860      +/-   ##
==========================================
- Coverage   81.45%   81.40%   -0.05%     
==========================================
  Files         464      464              
  Lines       29524    29524              
  Branches     3266     3266              
==========================================
- Hits        24048    24035      -13     
- Misses       4681     4695      +14     
+ Partials      795      794       -1     

Flag	Coverage Δ
Agent	82.31% <ø> (-0.05%)	⬇️
Profiler	73.33% <ø> (ø)

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see 3 files with indirect coverage changes

[tippmar-nr]

Good find!