The UI should be able access Eventing from any node

[Cloned for Eventing from MB-26993]

We have other issues open that are related to improving parts of this issue, but I want to open one issue to cover this problem in general because it affects the experience of our Kubernetes (and probably other) cloud deployments.

In the cloud we don't really care about which node we access to get to the UI and nodes may come and go so the ip address/host name we used to access the cluster yesterday might not be valid today. To mitigate this issue micro service architectures use a service discovery mechanism to allow the user to setup a permanent hostname that serves as a proxy to one of the nodes in a Couchbase cluster. This hostname will never change and as nodes come and go in the cluster we can update the proxy to correctly forward to a node in the cluster.

This solution however does not work in a MDS Couchbase cluster because we don't allow access to services not existing on the node we connected to.