[swarm-fedora-atomic] fix cluster etcd_lb protocol definition

In file drivers/swarm_fedora_atomic_v1/templates/cluster.yaml,
etcd_lb protocol is hardcoded:

  etcd_lb:
    type: ../../common/templates/lb.yaml
    properties:
      fixed_subnet: {get_attr: [network, fixed_subnet]}
      external_network: {get_param: external_network}
      protocol: HTTP
      port: 2379

but protocol should be: {get_param: loadbalancing_protocol}

Change-Id: Ib36ff0a99e219db9c0e0f35267faf317f5a14554
Closes-Bug: #1712054

magnum/drivers/swarm_fedora_atomic_v1/templates/cluster.yaml

@@ -281,7 +281,7 @@ resources:
     properties:
       fixed_subnet: {get_attr: [network, fixed_subnet]}
       external_network: {get_param: external_network}
-      protocol: HTTP
+      protocol: {get_param: loadbalancing_protocol}
       port: 2379
 
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