[BUGFIX] Remove nested form-group class

Remove nested class "form-group" in backend user module form

Resolves: #86450
Releases: master
Change-Id: I15a46b772d55ee8c0ea6fe9de00ef5a3cf53f27e
Reviewed-on: https://review.typo3.org/58468


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>