Adds BindCluster.spec.service.externalTrafficPolicy so DNS LoadBalancers
can preserve client source IPs (Local), which the source-IP ACLs on the
authoritative/resolver need to actually restrict external clients (Cluster
SNATs everything to node IPs).
- api: ClusterServiceSpec.externalTrafficPolicy (enum Cluster;Local)
- set it on the client Service for LoadBalancer/NodePort types
- regenerate CRDs + install.yaml