[BUGFIX] Save collapse-state of scheduler tasks groups

In scheduler module, tasks can be gathered in groups. Each group,
including the one for unassigned tasks, displays them in a table that
can be collapsed.
Groups can also be reordered.

Groups collapsed states and order are saved in UC.

Prior to this patch, collapsed states were wrongly saved because the
saved key for each table was based on the index of the group, which can
change depending on the groups order.
Now the saved key is using the group id which stays unique, except for
the unassigned tasks group which is always the first one (equivalent to
group id "0").

Resolves: #101167
Releases: main, 12.4
Change-Id: I78a1524891b5857329266c8b67eac503a56e97aa
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/86270


Tested-by: core-ci <typo3@b13.com>
Tested-by: Garvin Hicking <gh@faktor-e.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Tested-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Guido Schmechel <guido.schmechel@brandung.de>
Reviewed-by: Thomas Hohn <tho@gyldendal.dk>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Garvin Hicking <gh@faktor-e.de>