[TASK] Convert ExtendedFileUtilityTest to functional

Resolves: #98767
Releases: main
Change-Id: I5b2b9082e5e2a8264ed63f11a37255e586ea963e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76752


Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>