Add variant device_sda_selected needle for #1530410
    
    Rawhide has a bit of a problem where its 'description' of an
    iSCSI disk is so long that the other columns that should appear
    in the CONFIGURE MOUNT POINT dialog don't. This means our
    device_sda_selected needle doesn't match, because the column
    where 'sda' should appear isn't visible.
    
    So add a soft-fail needle to cover this case; we know what the
    description for the disk that's 'sda' in this case looks like,
    so match on that.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>