Add #openstack-infra to eavesdrop

There have been general requests for more logging of more things. I
think we might have a longer discussion there. But recently there have
been specific requests about -infra. I think that since discussions
around the gate and rather wide-spread project concerns wind up
happening in infra, we should definitely start logging it, and then we
can talk about whether other team channels should be logged or not.

Made this use an array of channels rather than a string for sanity.

Change-Id: I3f3e82aa86155d1ac3010ca3c3ade006b7a26793
Merge "Add #openstack-infra to eavesdrop"