munin/wormhole_event_rate: fix calculation of 'scary' and 'incomplete'
munin/wormhole_event_rate: fix calculation of 'scary' and 'incomplete'

I made a cut-and-paste error before, and these two values were derived from
'happy' instead of their own counts.

warner/magic-wormhole,warner/magic-wormhole,warner/magic-wormhole,warner/magic-wormhole