OpenTSDB: Disabled Ganglia support by default. (https://rbcommons.com/s/pepperdata/r/3524)
Users may send Ganglia 30x and Ganglia 31x protocol messages to the same port,
but the current implementation just supports Ganglia 30x and does not handle the
Ganglia 31x protocol messages. In addition, the default Ganglia port 8649 may
not be available for OpenTSDB when users are running Ganglia on the same node
with OpentSDB. So I disabled Ganglia support by default and reduced the log
levels to debug too. Users could enable it for some experiments with Ganglia 30x
protocol.