[BUGFIX] Ignore unique evaluation in l10n_mode exclude

[BUGFIX] Ignore unique evaluation in l10n_mode exclude

The l10n_mode "exclude" explains to copy the field value from
source language, so unique evaluation should be ignored for
translated records.

Resolves: #84267
Resolves: #83572
Releases: master, 8.7
Change-Id: I6a086cb1fc447dda2cbcfe27f33ba9f3dd714f53
Reviewed-on: https://review.typo3.org/56151
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>