[TASK] Make "N/A" translatable

The string "N/A" was hardcoded in BackendUtility
and has now been made translatable.

Resolves: #76361
Releases: master
Change-Id: I465956999fbbbcdc45175b59c42a5f1a2b31d4dc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63672


Tested-by: Björn Jacob <bjoern.jacob@tritum.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Björn Jacob <bjoern.jacob@tritum.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>