We will be rotating zk01-03.openstack.org out and replacing them with
zk04-06.opendev.org. This is the first change in that process which puts
zk04 into the rotation. This should only be landed when operators are
ready to manually stop zookeeper on zk03 (which is being replaced by
zk04 in this change).
Change-Id: Iea69130f6b3b2c8e54e3938c60e4a3295601c46f