[BUGFIX] Consider `translationSource` for fetching localized records

Using `transOrigPointerField` to fetch localized records does not work
for records that were copied into a different language via DataHandler's
`copyLanguage` command.

`BackendUtility::getRecordLocalization()` now takes `translationSource`
into consideration to fetch the appropriate localization of a record.

Resolves: #84951
Releases: master, 8.7
Change-Id: I8fc9ea3c1fdaf3e54110196c6a27411e0c66b366
Reviewed-on: https://review.typo3.org/56894


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>