[BUGFIX] Perform the translation key look-up as it was before #81775

[BUGFIX] Perform the translation key look-up as it was before #81775

If a form is rendered through the "form" content element,
the identifier of the form is modified with a suffix since #81775.
The translation key look-up must act like before #81775
and must perform the search for translation keys with the suffixed
form identifiers in addition.

Resolves: #84471
Releases: master
Change-Id: I92b708e1c392ad005c4a1bcd59f1c31788d7756f
Reviewed-on: https://review.typo3.org/56356
Tested-by: TYPO3com <no-reply@typo3.com>
Tested-by: Kay Strobach <typo3@kay-strobach.de>
Reviewed-by: Kay Strobach <typo3@kay-strobach.de>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>