[TASK] Make FileBackendTest.php notice free

Releases: master
Resolves: #84720
Change-Id: If13dfe85fcb41ce3a361fbb184d95c5ddffaf958
Reviewed-on: https://review.typo3.org/56654


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Thomas Maroschik <tmaroschik@dfau.de>
Tested-by: Thomas Maroschik <tmaroschik@dfau.de>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Kay Strobach <typo3@kay-strobach.de>
Tested-by: Kay Strobach <typo3@kay-strobach.de>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Tested-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>