3 backports to do

main	13.4	12.4
Merged #87976 [BUGFIX] Handle file upload validation for empty argument Author Georg Ringer Updated 1 month ago Affected Files 2 Patchsets 4 Reviews 4 Verifies 4	Review is missing.
Merged #87515 [BUGFIX] Update CKEditor model in source edit view on input Author Benjamin Franzke Updated 27 days ago Affected Files 2 Patchsets 10 Reviews 3 Verifies 3	Merged #88480 [BUGFIX] Update CKEditor model in source edit view on input 13.4 Author Benjamin Franzke Updated 27 days ago Affected Files 2 Patchsets 2 Reviews 2 Verifies 2	Review is missing.
Merged #88586 [BUGFIX] Properly check for sub schema Author Georg Ringer Updated 17 days ago Affected Files 1 Patchsets 2 Reviews 3 Verifies 3	Review is missing.