Add node label to etcd metrics (kubernetes-sigs#8475)

targetRef on endpoints surfaces as
__meta_kubernetes_endpoint_address_target_kind/__meta_kubernetes_endpoint_address_target_name
in prometheus and gets converted to the label `node` by
prometheus-operator

roles/kubernetes-apps/ansible/templates/etcd_metrics-endpoints.yml.j2

@@ -7,9 +7,12 @@ metadata:
     k8s-app: etcd
     app.kubernetes.io/managed-by: Kubespray
 subsets:
-{% for etcd_metrics_address in etcd_metrics_addresses.split(',') %}
+{% for etcd_metrics_address, etcd_host in etcd_metrics_addresses.split(',') | zip(etcd_hosts) %}
   - addresses:
       - ip: {{ etcd_metrics_address | urlsplit('hostname') }}
+        targetRef:
+          kind: Node
+          name: {{ etcd_host }}
     ports:
       - name: http-metrics
         port: {{ etcd_metrics_address | urlsplit('port') }}