Add RabbitMQ ingress Network Policy rules

The patch adds Network Policy ingress rules for RabbitMQ
and Prometheus RabbitMQ exporter.

It also fixes name generation for network policies,
to make sure they do not contain a prohibited '_' symbol,
which may appear in some label names.

Change-Id: I9821983b61d90e73e62c5ac669eefeb4ba9999d2

rabbitmq/values.yaml

@@ -319,6 +319,11 @@ endpoints:
         protocol: UDP
 
 network_policy:
+  prometheus_rabbitmq_exporter:
+    ingress:
+      - {}
+    egress:
+      - {}
   rabbitmq:
     ingress:
       - {}
@@ -346,6 +351,7 @@ manifests:
       configmap_bin: true
       deployment_exporter: true
       service_exporter: true
+      network_policy_exporter: false
   network_policy: false
   secret_erlang_cookie: true
   secret_admin_user: true