Remove cluster_enabled setting for etcd
Remove cluster_enabled setting for etcd

Setting cluster_enabled to false causes ETCD_INITIAL_ADVERTISE_PEER_URLS
to be unset, which will cause deployment failure when etcd is deployed
in a single node mode.

Closes-Bug: #1673188

Change-Id: Iadff36bf7beb247d0408913c89f83fa5c8ac6874
Signed-off-by: Feng Pan <10d7d91a403737f0faecf20d08873f2a73403172@redhat.com>

openstack/puppet-tripleo,openstack/puppet-tripleo,openstack/puppet-tripleo