[BUGFIX] Failing group/select test changeElementSorting

The workspace modify test "changeElementSorting" is failing
in the frontend for the TCA types "select" and "group".

The reason is, that the move placeholder is not selected
via the "uidInList" TypoScript property and thus removed
in PageRepository::versionOL().

To avoid that, "uidInList" gets extended to look-up
move placeholders if versioning preview is enabled.

Resolves: #56782
Releases: 6.2
Change-Id: Ifae30527bead02b38888f326de2615f6bfe35f5b