[TASK] Add test method prefix checker to gitlab-ci

Test methods are not allowed to have a prefix "test".
Use the annotation "@test" in phpDoc instead.

Integration into pre-merge and nightly gitlab-ci suites.

Note we now have multiple tests based on nikic/php-parser.
Those should be rewritten to use one parser instance with
multiple visitors to scan php code only once. The
exception code checker should be rewritten to use
the parser, too. This will be done with a dedicated patch.

Resolves: #94859
Releases: master
Change-Id: I43ba692eaf2a342a2e0ed3d8978386ea5719183f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70524


Tested-by: waldhacker <hello@waldhacker.dev>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: waldhacker <hello@waldhacker.dev>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>