[TASK] add acceptence tests for filter backend user in backend module

Resolves: #77823
Releases: master
Change-Id: I301c43c4429bf18fde4c65c9d12c94951693bfc4
Reviewed-on: https://review.typo3.org/49829


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Valentin Funk <valentin.funk@computerfabrik.de>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Marco Bresch <marco.bresch@starfinanz.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>