[BUGFIX] TCA field using MM table is incorrectly duplicates relations

The previous change disabled the lookup on the parent UID which resulted
in getting all possible relations due to the missing constraint. Now the
behavior is mitigated by resetting non-numeric values to zero which will
lead to an empty result set - like implicitly for MySQL before.

Resolved: #80172
Releases: master
Change-Id: If6c8d2e3b2c2b2ddf15727196f7da294fe2ada06
Reviewed-on: https://review.typo3.org/51978


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Thomas Hohn <thomas@hohn.dk>
Tested-by: Thomas Hohn <thomas@hohn.dk>
Reviewed-by: Marcus Schwemer <ms@schwemer.de>
Tested-by: Marcus Schwemer <ms@schwemer.de>
Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>