[BUGFIX] Avoid cHash mismatches when previewing workspace changes

In order to avoid cHash mismatches URL parameter 'ADMCMD_prev' is
not being used for cHash calculation anymore.

Resolves: #87995
Releases: master, 9.5
Change-Id: Ifefefc873478759a15aed786e16b062e28c739f9
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/60327


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benjamin Franzke <bfr@qbus.de>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benjamin Franzke <bfr@qbus.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>