[TASK] Drop CKEditor4 related resources

Some plugins and integrations have been kept on purpose
in #96874, in order to keep the patch small.

All CKEditor4 related infrastructure is now removed as it is unused.

Resolves: #98497
Related: #96874
Releases: main
Change-Id: Iedfe53fbb102b28be5127c1c5fbd4d8877507e7f
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75937


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>