ovirt-foreign-menu: Fix endpoint for storage domains query
    
    Instead of fetching toplevel REST API query, we use the one relative
    from the data center, which returns more detailed information,
    especially the status of the storage domain.
    
    This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1427467
    
    Signed-off-by: Eduardo Lima (Etrunko) <etrunko@redhat.com>
    Acked-by: Victor Toso <victortoso@redhat.com>