[BUGFIX] EXT:Scheduler: Update storage index saves correct storage

When creating an "update storage index" task, now the selected storage
is saved correct.

Resolves: #67241
Releases: master
Change-Id: I371c5aa882ff78095536f1e413d58850ccb46c2b
Reviewed-on: https://review.typo3.org/51036


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>