[BUGFIX] Don't update language icon if not in language mode

The page module now doesn't try to update the flag icon of a dragged
record if the page module is not in "language" mode as the required
information is not available.

Resolves: #91096
Related: #90693
Releases: master
Change-Id: I1c796a6f4b00761f3310335cf45256d75a7e3bc5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/64218


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Richard Haeser <richard@maxserv.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Christian Eßl <indy.essl@gmail.com>
Reviewed-by: Richard Haeser <richard@maxserv.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Christian Eßl <indy.essl@gmail.com>