[BUGFIX] Filename sorting in filelist is broken

The sorting by filename in the filelist is broken since the
introduction of sys_file_metadata. It tries to sort the file list
by property file. Before sys_file_metadata it couldn't find this
property and sorted by the default value name. But after introduction
of sys_file_metadata it has an property file, his own sys_file uid.

This patch fixes the sorting behaviour when sorting by filename.

Resolves: #56128
Releases: 6.2
Change-Id: Icd25bc2aafed4baafbaa7d9f87ce755fe9e64579
Reviewed-on: https://review.typo3.org/27881
Reviewed-by: Markus Klein
Tested-by: Markus Klein
Reviewed-by: Alexander Opitz
Tested-by: Alexander Opitz
Reviewed-by: Stefan Froemken
Tested-by: Stefan Froemken
Reviewed-by: Frans Saris
Tested-by: Frans Saris