[BUGFIX] Re-add initialization of PageRepository::$where_groupAccess

Re-added `$this->where_groupAccess` to init method.

Resolves: #91429
Releases: master, 9.5
Change-Id: Ibd9b169e8d11e358023d8cfbd2085995769d16cc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64516


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>