[TASK] Remove deprecated code from "about" and "aboutmodules"

Remove deprecated code from "about" and "aboutmodules"

Change-Id: I2296d4039ce8ffd16a39c3643365886b1f696a69
Resolves: #44761
Releases: 6.1
Reviewed-on: https://review.typo3.org/16843
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn