[TASK] Make FileSizeValidatorTest.php notice free

Resolves: #84350
Releases: master
Change-Id: I4ab0027f86517f6f607a891a2ad5a1417935af1b
Reviewed-on: https://review.typo3.org/56231


Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>