[TASK] Consistent date and time rendering in FormEngine

Use methods of BackendUtility to have a consistent look of date and
time fields in the backend.

Resolves: #85002
Releases: master, 8.7
Change-Id: I6f0b6aca1530524ff3f83922a1b4b2dd72b1ea84
Reviewed-on: https://review.typo3.org/57041


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>