[nextest-runner] don't try and hide progress between stress sub runs

[sunshowers]

Fixes #2764.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 78.61%. Comparing base (cca8c2e) to head (4bd652e).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
nextest-runner/src/reporter/displayer/progress.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2765      +/-   ##
==========================================
+ Coverage   78.57%   78.61%   +0.03%     
==========================================
  Files         112      112              
  Lines       26231    26219      -12     
==========================================
  Hits        20611    20611              
+ Misses       5620     5608      -12     

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