[TASK] Use LanguageService in EXT:form TranslationService

LanguageService can also be used
for overriding labels via TypoScript.

For this reason, TranslationService from
EXT:form can be slimmed down similar
to how Extbase's TranslationUtility was
migrated in:
https://review.typo3.org/c/Packages/TYPO3.CMS/+/77399

Because TranslationService does not have
an input for alternative language keys,
the dependency functionality from
LanguageService can be used.

Resolves: #99566
Releases: main
Change-Id: I76536087d2210bbd4d47fc9119abd86af3348a9c
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77412


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>