[TASK] Remove unreachable code

This patch removes the old workspace and most of the old version
module. This patch was already done for 4.6 with commit 73932aedacd27
"Removed unused workspace code" but commit 76b0908d80c5d introduced
it again by accident.
This patch now replays the removal of commit 73932aedacd27

Change-Id: I76804c0231a4c95bd0eedfc7e5ff2f21999fe577
Releases: 6.1
Resolves: #46516
Reviewed-on: https://review.typo3.org/19151
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn