[CLEANUP] Follow up: Rename dividers2tabs rst file

dividers2tabs was removed with #62833. The ReST manual file is titled
"Deprecation", but the content says "Breaking". Rename the file.

Resolves: #62844
Releases: master
Change-Id: Id7c9750fe6b204e5ec1995604f6d6d9099b0f1fb
Reviewed-on: http://review.typo3.org/33974
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>
[BUGFIX] Make other framesets in BE work again

Similar to ElementBrowser, the other
parts where <frameset> is used don't
work right now. This needs to be fixed.

Resolves: #62834
Related: #62825
Releases: master
Change-Id: Ic7e39bd4e4eb7f8326e4f16b379330aa95081eed
Reviewed-on: http://review.typo3.org/33959
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Frank Nägler <typo3@naegler.net>
Tested-by: Frank Nägler <typo3@naegler.net>