Previously, we had the following configuration in Psalm, which I thought would still validate Builders in the Trackers unit test folder. It does not work, it turns out everything is still ignored.

<projectFiles>
  <directory name="plugins/*/tests/unit/" />
  <directory name="plugins/tracker/tests/unit/Builders" />
  <ignoreFiles>
    <directory name="plugins/tracker/tests/unit/"/>
  </ignoreFiles>
</projectFiles>

We should instead let Psalm validate all unit tests, and selectively ignore each folder/file that has errors. This way, new files will be correctly validated, and old files can be un-ignored surgically. We should also add the existing errors from stubs and builders to the baseline file, so that they will hopefully be corrected gradually.