Drop similarity levels on type(_very)_safely, solidify_wallpaper
    
    I noticed today that we're timing out all the time on these
    wait_still_screens in gnome-terminal, because it uses a big
    flashing cursor and the similarity between "cursor there" and
    "cursor not there" is less than 45 or 42 (it seems to be 38.x).
    So let's drop these levels to 38, hopefully that's not too low.
    There are probably more places where this is an issue, I'll
    change them as I notice them.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>