[BUGFIX] Fix message "Translate to"

Reset the variable to be able to set the text "Translate to" for
multiple fields.

Resolves: #77506
Releases: master, 7.6
Change-Id: I6b18f30ece04ae5cf5710617dbbc5ea2c0855ad6
Reviewed-on: https://review.typo3.org/49499


Tested-by: Bamboo TYPO3com <info@typo3.com>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Tested-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>