[BUGFIX] BackendUtility should not use PageRepository

BackendUtility builds a PageRepository object to fetch a SQL query instead
of simply using the Deleted+HiddenRestriction themselves to fetch the first fe_group
record.

The PageRepository object does not even get initialized, so it can safely be exchanged.

Releases: master
Resolves: #81032
Change-Id: I4279f189c5c42c763aeeb3f519326677e94bd160
Reviewed-on: https://review.typo3.org/52627


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>