[!!!][TASK] RTE Transformations: Remove manual tag mapping functionality

More methods were removed that were only used for the old "ts"
transformations and have been tackled differently since the
introduction of "ts_css" transformations.

Resolves: #72888
Releases: master
Change-Id: I5315e57e1654af66f48fe5df807b9b57ca0382d9
Reviewed-on: https://review.typo3.org/46144


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Markus Sommer <markussom@posteo.de>
Tested-by: Markus Sommer <markussom@posteo.de>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>