Ensure base test classes don't have class level phpunit metadata

I suggest to wait for conversions of annotations to attributes to be completed, then check on attributes instead. Probably a PHPStan rule should be written here.

Changed mind and added a PHPStan rule checking for either annotations or attributes on abstract test base classes. We have 17. errors to be solved.

Curious why did the baseline change?

Because fixing the errors that this rule surfaces is not trivial. So better leave that to follow ups IMHO, while the rule prevents adding more leaks.

Oh I was just curious not that they should be fixed

Well, the new rule introduces new errors, so either we fix them or we baseline them :)

Only other question is should annotations be attributes or does it not matter

A check to prevent the use of annotation is already done by PHPUnit itself when it is configured to fail on PHPUnit deprecations. See #3534156: Complete test annotations to attributes conversion for Drupal/Test/Component for an example.

IMHO we should not replicate such a check here.

In that case I'll go on a limb and say this one is probably ready.

Because I think we should check if the extending classes have the metadata implemented as the base class, and if not see why not and possibly convert to attributes.

Let's simplify - we do not have to list all the attributes, we can just check that no attributes in the namespace PHPUnit\Framework\Attributes are present - this also leaves space to additional attributes introduced by PHPUnit w/out needing to come back to this rule.

This probably would of been good to get in earlier, sorry it fell off my radar.