apps_startstop: tweak print theme editor launch to avoid #2165657
    
    Typing a partial binary name no longer seems to work. Typing the
    full binary name works, but differently from before; seems best
    to do a partial entry name search so we launch the actual entry,
    not the executable directly.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>