[TASK] Remove unused variables in FormEngine InputTextElement

There are several datetime related configuration
settings which are not in use.

Resolves: #72824
Releases: master
Change-Id: I68d3c9725ca74ebe79a627d1fa59f6c60283d266
Reviewed-on: https://review.typo3.org/46102


Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>