Use api lookup for kubelet hostname when using cloudprovider (#1686)

The value cannot be determined properly via local facts, so
checking k8s api is the most reliable way to look up what hostname
is used when using a cloudprovider.

roles/network_plugin/calico/templates/cni-calico.conf.j2

@@ -1,7 +1,7 @@
 {
   "name": "calico-k8s-network",
 {% if cloud_provider is defined %}
-  "nodename": "{{ inventory_hostname }}",
+  "nodename": "{{ calico_kubelet_name.stdout }}",
 {% else %}
   "nodename": "{{ ansible_hostname }}",
 {% endif %}