Exclude remote file systems from inspection of unmanaged files

Remote file systems are all file systems which are mounted either via NFS or
CIFS, directly or via the auto mounter. These file systems are not extracted
by the unmanaged-files inspector. The mount points of remote file systems are
stored as entry of type 'remote-dir' in the unmanaged-files scope in the
system description.
`mounts_abs` is only really used in line 268. I would just get rid of this redundant variable instead.

Thinking about it, apparently `mounts` contained relative paths before and with the new `Mounts` class it contains absolute ones. Doesn't that affect the result of the inspector in some way? Looking at lines 273-279 it seems as if mount points wouldn't be considered unmanaged dirs anymore because the names shouldn't match, no?