[BUGFIX] Rotate finisher dropdown indicator

Rotate collapse arrow 90 degrees for expanded validators and finishers.
Remove this indicator when there is no panel to expand.

Resolves: #97041
Releases: main
Change-Id: I184deca19b34075e2706d112e48d40a9ab5bfcd2
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/73724


Tested-by: core-ci <typo3@b13.com>
Tested-by: waldhacker <hello@waldhacker.dev>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: waldhacker <hello@waldhacker.dev>
Reviewed-by: Benni Mack <benni@typo3.org>