[BUGFIX] Remove duplicated caret and re-add padding

* Removes duplicated dropdown caret and use bootstraps
  css caret (gridelement inside/after and finisher)
* Fix preview mode dropdown in workspaces

Resolves: #94198
Releases: master
Change-Id: I7785f3ce21a6ee9773ebcd192b7a6abaded57273
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/69266


Tested-by: core-ci <typo3@b13.com>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>