[BUGFIX] Handle the CKEditor5 option removePlugins properly

The removePlugins option needs to be assigned
as an array in CKEditor5. While we recommended
passing the option already as an array, CKEditor4
needed a comma-separated string.

The conversion was only handled if the Integrator
passed an array, which means if someone already
provided a comma-separated string the option
was simply passed as is to the Editor.

To avoid javascript errors we are going to migrate
it to array for now. The possibility to pass the option
as a string is deprecated and will be removed with
version 13.

Resolves: #98613
Releases: main
Change-Id: I36900917d751b0c47ea2f4a3256f3faade21f3f7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/76114


Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Benni Mack <benni@typo3.org>