[BUGFIX] Correctly define allowedSubProperties of TwitterCardMetaTagManager

The properties within the allowedSubProperties have to be arrays
because the AbstractMetaTagManager checks if the property as a key
exists in the allowSubProperties.

Resolves: #85126
Releases: master
Change-Id: Ie57a77f8d4100e0861958de73faa56d80709daad
Reviewed-on: https://review.typo3.org/57099


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Tested-by: Mona Muzaffar <mona.muzaffar@gmx.de>
Reviewed-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Tested-by: Anja Leichsenring <aleichsenring@ab-softlab.de>
Reviewed-by: Jigal van Hemert <jigal.van.hemert@typo3.org>
Tested-by: Jigal van Hemert <jigal.van.hemert@typo3.org>