EventLogging Ganglia monitor: collect every 10 seconds (was: 30)

collect_every was set to 10 seconds until I7122cad6e, where I changed it to 30.
For reasons I don't entirely comprehend, this made the graph appear 'jittery'
(for lack of a better word), with every second datapoint appearing to be
skewed.

Change-Id: Ifc70d1983a918e9897d487bee029a7b488185e9a
Merge "EventLogging Ganglia monitor: collect every 10 seconds (was: 30)" into production