/metrics endpoint is publicly exposed

[pricejc-sublime]

It looks like port 10254 is set up to always be added to the Service created by the operator based on https://github.com/Azure/aks-app-routing-operator/blob/main/pkg/manifests/nginx.go#L316. This causes the /metrics endpoint to be publicly exposed by the load balancer. I believe this may be undesirable as that endpoint could leak information.

[zioproto]

Cc: @sabbour

[sabbour]

Fix coming: #295