[BUGFIX] Mark objectstorage clean after saving

Release: 6.1, 6.0, 4.7
Fixes: #36103
Change-Id: Id1bbe3397e18105a51de751c4fbccad55d34a47e
Reviewed-on: https://review.typo3.org/19947
Reviewed-by: Wouter Wolters
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer