[!!!][TASK] Remove auto-unpublishing of workspaces

Workspaces had a field called "unpublish_time" which was not accessible
for TYPO3 Core since TYPO3 4.5. The field was still processed, but never
in use due to side-effects.

The functionality has therefore been removed without substitution.

Resolves: #81950
Releases: master
Change-Id: I6d79b78246103ef485a4d9d0de791b03d10d08a5
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60482


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>