In Ibbb430fb1dbf66942168e0cb52d990ab6a2eb8d7, we are adding
etcd3 as a new base service. We should drop zookeeper
and use etcd3 as the backend.
Since cinder is the first service for this tooz+etcd3 DLM
scenario and cinder uses eventlet we have cannnot use the
grpc based driver in tooz. So new CINDER_COORDINATION_URL
that defaults to the etcd3's grpc HTTP gateway based
tooz backend.
We need to hold this change until the tooz change (see
Depends-On) is available in a tooz release.
Depends-On: I6184ed193482dad9643ccb2b97133d4957485408
Change-Id: Ia187e1a86413edf25b909b6bb57e84fb4930a696
c0d16c279a