Instead of passing down `transport` in DelegateTransport, I think we should pass in there the actual transport used (local or netty). Right now a stack overflow can happen if LookupTestTransport#getTransport(DiscoveryNode) has a miss in its `transports` map.

If we keep track of the actual Transport used in this class by saving it in a field which the constructor sets and we use that one instead then the stackoverflow can't happen.