[BUGFIX] Extbase: correct handling of mm relations

This change fixes a regression after the doctrine migration and additionally
fixes a wrong join condition which is also present in version 7

Resolves: #79931
Resolves: #79932
Releases: master
Change-Id: I04a4ce174fb1da3baca9af8ba771a7db70d9a884
Reviewed-on: https://review.typo3.org/51782


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>