CoreDNS support EndpointSlices

In order to properly support EndpointSlices, enhance ClusterRole.

story: 2009874
task: 44582
Signed-off-by: Daniel Meyerholt <[email protected]>
Change-Id: Ib9d81e8d215bb50cb0d80b954949012cbbf45a5c

Author: Daniel Meyerholt

magnum/drivers/common/templates/kubernetes/fragments/core-dns-service.sh

@@ -40,6 +40,13 @@ rules:
   - nodes
   verbs:
   - get
+- apiGroups:
+  - discovery.k8s.io
+  resources:
+  - endpointslices
+  verbs:
+  - list
+  - watch
 ---
 apiVersion: rbac.authorization.k8s.io/v1
 kind: ClusterRoleBinding