\Drupal\Tests\Core\Test\PhpUnitCliTest requires a database and webserver - move to a functional test

There are two tests in that class; I think testPhpUnitListTests should remain a Unit test, because it is meant to identify if there are class duplications by running PHPUnit's test discovery. That serves the purpose of ensuring if you run a test group in PHPUnit CLI and not through run-tests.sh, you do not incure in fatal errors.

testFunctionalTestDebugHtmlOutput on the other hand yes, it could be split into a FunctionalTest.

This is outdated now, testFunctionalTestDebugHtmlOutput was moved in another issue.

However, there are other tests currently requiring a db, and the 'with webserver' requirement for unit tests cannot be reverted.

Not closing the issue as it’s referenced in pipeline.yml; however a new issue is needed.

Replacement issue: 📌 [CI] Remove the 'with-database' requirement for unit tests Active

This was fixed in the related issue.