[BUGFIX] Fix styling for various Backend items

Due to the Bootstrap Update, some custom functionality
by TYPO3 is not needed anymore and can be simplified:

* No need for caret in SplitButton anymore (Clipboard, History)
* Simplified horizontal filter menu (TSOB, Indexed Search Menu)
* Better grid in EXT:forms module
* Adjustments to autocomplete / FormEngine suggest field

Resolves: #93137
Releases: master
Change-Id: Ib7ff72832ea7223d2ba6ae31704c7f33f0e12bc1
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/67222


Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>