[BUGFIX] Fix RTE width

edit_wideDocument option has been removed with #57295 but it was forgotten
to adjust RTE accordingly.

Wide screens are default now, so we remove the check for this option
also in RTE. Furthermore the settings for small screens are superfluous
too.

Documentation is adjusted as well.

Resolves: #59692
Releases: 6.3, 6.2
Change-Id: I9bb5fc2a892f3de446137856e9fa18317f40b5c1
Reviewed-on: https://review.typo3.org/31274
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters