[BUGFIX] Respect site for route persisted mappers

When a slug is unique in site, we need to check whether
the slug found in the database is part of the current site,
otherwise it must be discarded.

Resolves: #88720
Releases: master, 9.5
Change-Id: I469d7b853f75eec09463bb809b795c4732753cff
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/61585


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Jonas Eberle <flightvision@googlemail.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>