[BUGFIX] Can not delete Files with metadata records

When a sys_file record has relation with a sys_file_metadata
record the file can not be deleted.

This patch excludes tables sys_file_metadata from the
reference check.

Resolves: #53672
Releases: 6.2
Change-Id: Ib7a5b55fce9f5cf19ffe3b18eddfc7238a8e8626
Reviewed-on: https://review.typo3.org/25456
Reviewed-by: Alexander Opitz
Tested-by: Alexander Opitz
Reviewed-by: Fabien Udriot
Reviewed-by: Markus Klein
Tested-by: Markus Klein