[BUGFIX] OnlineMedia: Check correctly if image processing is enabled

This is a regression fix after #43085, which missed on place to adjust.

Resolves: #72839
Releases: master
Change-Id: Icc71db034245ebba1732d539f746e481031de312
Reviewed-on: https://review.typo3.org/46110


Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>