[BUGFIX] Unify backend routes for workspace

Resolves: #103212
Releases: main, 12.4
Change-Id: If285a5cb1bb418ef7671ca6894827a059e5c1cb7
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84741


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>