Use 10250 as targetPort for metrics-server

Metrics-server's usage of privileged port 443 as targetPort requires
elevated permissions than necessary and violates principle of least
privilege.

cluster/addons/metrics-server/metrics-server-deployment.yaml

@@ -58,9 +58,9 @@ spec:
         - --kubelet-insecure-tls
         - --kubelet-preferred-address-types=InternalIP,Hostname,InternalDNS,ExternalDNS,ExternalIP
         - --cert-dir=/tmp
-        - --secure-port=443
+        - --secure-port=10250
         ports:
-        - containerPort: 443
+        - containerPort: 10250
           name: https
           protocol: TCP
         readinessProbe: