Elasticsearch plugin juggling

This instructs cirrus to stop using the hebrew plugin on next index rebuild
in beta.  It'll use the icu plugin instead.  This also instructs it not to
use the icu plugin in production becase we'd like to try it in beta first.

Change-Id: Iae07852b1f96765a5fd8a909ff42aee55ad90d0e
Merge "Elasticsearch plugin juggling"