[BUGFIX] Add correct conversion of RTE pageTS config

Add all pageTS.RTE options to config without dots appended to the key
to be able to override the RTE config with pageTS like before.

Resolves: #82865
Releases: master, 8,7
Change-Id: Idb7d7d3b39d44ec37be8f93cc9de8b42b9c8a55c
Reviewed-on: https://review.typo3.org/54511


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Reviewed-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>
Tested-by: Stefan Neufeind <typo3.neufeind@speedpartner.de>