[TASK] Remove deprecated code

Remove deprecated code that is marked to be deleted in 6.1.

Change-Id: I4a8f512c039e537733228840f1fb8a592f8331a3
Resolves: #44763
Releases: 6.1
Reviewed-on: https://review.typo3.org/17676
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn