Install k8s after OpenStack services up

In plugin.sh we install kubernetes at devstack post-config phase, at that
time all of the OpenStack services are not launched yet, so plugin.sh
script don't have chance to get subnet-id or floating-network-id for
external cloud provider config file cloud-config, we want to get these
information to make cloud-config file, then execute local-up-cluster.sh
to launch kubernetes with external cloud provider.

Author: kiwik

devstack/plugin.sh

@@ -168,11 +168,11 @@ if is_service_enabled k8s-cloud-provider; then
         install_prereqs
 
     elif [[ "$1" == "stack" && "$2" == "post-config"  ]]; then
-        install_k8s_cloud_provider
-
-    elif [[ "$1" == "stack" && "$2" == "extra"  ]]; then
         # no-op
         :
+    elif [[ "$1" == "stack" && "$2" == "extra"  ]]; then
+        install_k8s_cloud_provider
+        :
     fi
 
     if [[ "$1" == "unstack"  ]]; then