[!!!][CLEANUP] Remove deprecated code in sysext extbase

Resolves: #62673
Releases: master
Change-Id: If468f183fa0e31624e7bf4621728066d4e770066
Reviewed-on: http://review.typo3.org/33771
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>