Raise the Elasticsearch refresh interval

This should lower load on Elasticsearch at the cost of making search updates
slightly less real time.  30 seconds shouldn't be _too_ long.

Needs Ib8aecec5b6cf0b9a2f93bf774f7078a566f173ac in Cirrus.

Change-Id: I57ef339830d58cbcd7d53ccfc0da630197dd67fe