[TASK] Doctrine: Migrate Extbase DB backend Part 2

The method getUidOfAlreadyPersistedValueObject() is migrated
to doctrine.

During the change, it was noticable that the calls to the deprecated
protected methods addVisibilityConstraintStatement(),
getBackendConstraintStatement() and getFrontendConstraintStatement()
are not needed at all, and are removed, as the RestrictionBuilder
is taking care of that functionality transparently.

Resolves: #77476
Releases: master
Change-Id: Ib89abd6e5155f5caeb9d06b452aba77ac39444b1
Reviewed-on: https://review.typo3.org/49436


Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>