configure cluster-name for hubble relay (#10614)

roles/network_plugin/cilium/templates/hubble/config.yml.j2

@@ -8,6 +8,7 @@ metadata:
   namespace: kube-system
 data:
   config.yaml: |
+    cluster-name: "{{ cilium_cluster_name }}"
     peer-service: "hubble-peer.kube-system.svc.{{ dns_domain }}:443"
     listen-address: :4245
     metrics-listen-address: ":9966"