[TASK] Remove deprecated code from ext:workspaces

* remove rewritten toolbar item (#62800)
* remove rewritten notification parts (#35245)

Resolves: #72464
Releases: master
Change-Id: If2882bfc8c4bf47608cdec50ac30f5d9dbaeec12
Reviewed-on: https://review.typo3.org/45372


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Oliver Hader <oliver.hader@typo3.org>
Tested-by: Oliver Hader <oliver.hader@typo3.org>