[TASK] Refer to SimpleDataHandlerController instead of tce_db.php

Update comments in the code not to mention tce_db.php.

The tce_db.php entry point is gone since v8.
The SimpleDataHandlerController is responsible for pushing data
from request to DataHandler.

Resolves: #85600
Releases: master, 8.7
Change-Id: I6d323a9aab77ab67ff811970ff3c0f47dbf84340
Reviewed-on: https://review.typo3.org/57636


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Jörg Bösche <typo3@joergboesche.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>