Add etcd group support to rke role

Etcd cluster is now placed in members of kubernetes-etcd group instead
of kubernetes-node.
Due to defaults, it means infra is the only etcd
by default.

Change-Id: Iae05a42442849e4a248d73c2d78f5e2b0eae7255
Issue-ID: OOM-1778
Signed-off-by: Michal Zegan <m.zegan@samsung.com>
diff --git a/ansible/roles/rke/templates/cluster.yml.j2 b/ansible/roles/rke/templates/cluster.yml.j2
index f28cff8..2012ab9 100644
--- a/ansible/roles/rke/templates/cluster.yml.j2
+++ b/ansible/roles/rke/templates/cluster.yml.j2
@@ -9,6 +9,8 @@
 {% endif %}
 {% if node in groups['kubernetes-node'] %}
   - worker
+{% endif %}
+{% if node in groups['kubernetes-etcd'] %}
   - etcd
 {% endif %}
   hostname_override: ""