[TASK] Improve PathUtility tests

Add more test cases found when running mutation tests.


Resolves: #100532
Releases: master, 11.5
Change-Id: I3dc61e303351d4f63b4b4ad757f21188f1e60117
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78552


Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>