fix(cert-manager): Fix kustomize object matching

Kustomize selects the objects before rendering them, therefore the
included file should really address the same target, in this case
without a namespace.

infrastructure/cert-manager/networkpolicy-patch.yaml

@@ -3,7 +3,6 @@ apiVersion: networking.k8s.io/v1
 kind: NetworkPolicy
 metadata:
   name: allow-from-monitoring
-  namespace: cert-manager
 spec:
   podSelector:
     matchLabels: