drive-menu: Don't assume mounts without volume are local

The intention of the code is to only expose actually plugged in
devices rather than network mounts, but the existing heuristics are
based on GVolume and simply assume a local mount where there's no
associated volume. Fill that gap by querying the ::remote filesystem
attribute in that case.

1 job for wip/fmuellner/53-hide-network-mounts in 4 minutes and 38 seconds (queued for 95 minutes and 9 seconds)
Status Job ID Name Coverage
passed #6947