Create headless service for Dragonfly

Hello! We're using dragonfly in environment with restricted network policies based on Cilium and Istio.

For now we met with next issues in dragonfly operator that make such usage hard:

- Headless service for Dragonfly not created. Without it Istio not detect pods in service registry and I cannot allow traffic flow from operator to pod
- Port names cannot be configured. Istio recommends specify explicit protocol in appProtocol field or in service port name https://istio.io/latest/docs/ops/configuration/traffic-management/protocol-selection/