[TASK] Preparation for TER release

Remove legacy stuff related to not supported versions

Releases: 6.2
Change-Id: Iab70beb2fd8e5068401990063dc19e6043e9b91e
Reviewed-on: https://review.typo3.org/29528
Reviewed-by: Nico de Haen
Tested-by: Nico de Haen