MAINT: only rerun failed tests even if everything passes

[bsipocz]

This was a bug for the cases when all tests are passing and --last-failed was used as its default is to rerun everything again.

(It never was really an issue in CI as we always have some failing tests, but it made testing with only one or a few modules problematic)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.51%. Comparing base (9b784ab) to head (52b94d7).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3405   +/-   ##
=======================================
  Coverage   70.51%   70.51%           
=======================================
  Files         232      232           
  Lines       19997    19997           
=======================================
  Hits        14100    14100           
  Misses       5897     5897           

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