fix(shared): Reduce scope for monitoring NetworkPolicy

This patch reduces the network access from the monitoring namespaces to
only prometheus.

shared/networkpolicies/allow-from-monitoring.yaml

@@ -10,3 +10,6 @@ spec:
     - namespaceSelector:
         matchLabels:
           monitoring.shivering-isles.com/network-access-required: "true"
+      podSelector:
+        matchLabels:
+          app.kubernetes.io/name: prometheus