[BUGFIX] use media type name in metaExtract service calls

When no metaExtract service for a file's extension exists,
the media type ("image:*") is used as fallback.

This was broken as it only used the numeric media type ID instead
of the name ("2:*" instead of "image:*").

Change-Id: Idb56d88904842546b361a887511c2103ffd6324d
Fixes: #54149
Releases: 1.3
Reviewed-on: https://review.typo3.org/26508
Reviewed-by: Lorenz Ulrich
Tested-by: Lorenz Ulrich