neonvm/multus-aks: Fix ineffectual secret namespace (#1224)

Follow-up to #1202, namespace should be under the metadata field.
Without this, kubectl says 'Warning: unknown field "namespace"' and
tries to create the secret in the default namespace (not what we want).

neonvm/config/multus-aks/secret.yaml

@@ -1,8 +1,8 @@
 apiVersion: v1
 kind: Secret
 type: kubernetes.io/service-account-token
-namespace: kube-system
 metadata:
   name: multus-long-lived
+  namespace: kube-system
   annotations:
     kubernetes.io/service-account.name: multus