[BUGFIX] Use correct variable name in OnlineMedia.ts

Resolves: #86630
Releases: master, 8.7
Change-Id: I4bce2665ed54cddc3a151445c5863c24ffac6df6
Reviewed-on: https://review.typo3.org/58619


Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>