[BUGFIX] Avoid clipped dropdowns in btn-groups

The tables within the TYPO3 backend are wrapped within an element with overflow to enable scrolling and make them usable on smaller viewports.
The dropdowns with the TYPO3 backend are used in conjunction with button groups as a container that defines the position for child elements relative to the group. While non of these definition is a problem in it self, it leads to clipping dropdowns when used in combination.

Dropdown positions are calculated with JavaScript and placed absolute to the next relative container. Since the next container is inside the table that overflows, the dropdown display is cut off.

To resolve the issue for all placements, we define the standard behavior of button groups to be static. The parent container to calculate is now outside the table wrapper and the dropdown fully visible.

Resolves: #99914
Releases: main
Change-Id: I76258852a9984bfce136b54669e90d6fd4967e42
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/77820


Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>