[BUGFIX] Scheduler: Removed call to deprecated method render()

Call of FlashMessage->render() when configuring a task with the class
"File Abstraction Layer: Extract metadata in storage" for the
"Registered extractors" was replaced with appropriate code.

Resolves: #73685
Releases: master, 7.6
Change-Id: I1265ad845c2e951c9a5a242f74fa336a26645a88
Reviewed-on: https://review.typo3.org/46900


Reviewed-by: Frank Naegler <frank.naegler@typo3.org>
Tested-by: Frank Naegler <frank.naegler@typo3.org>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>