[BUGFIX] Element browser doesn't use FAL info to for file dimensions

The dimensions of a file are fetch during indexing. These values
should be used as for remote files or certain filetype getimagesize()
will not work or give unwanted overhead.

Resolves: #56864
Releases: 6.2
Change-Id: I14ece9c0dbf414f4cb0759d3065a1c5b5782ca29
Reviewed-on: https://review.typo3.org/28404
Reviewed-by: Markus Klein
Reviewed-by: Tomita Militaru
Reviewed-by: Wouter Wolters
Reviewed-by: Dmitry Dulepov
Tested-by: Dmitry Dulepov
Tested-by: Markus Klein