gitserver: discover endpoints dynamically in k8s
Created by: tsenart
This commit makes it so GitServers in ServiceConnections are discovered dynamically in Kubernetes clusters. We re-use the service discovery code from the endpoint package, without leveraging the consistent hashing part yet, which is for the time being still handled in gitserver client (i.e. AddrForRepo).
This should make unnecessary for customers to manually configure SRC_GIT_SERVERS in Kubernetes clusters.