dns agent: server should be served over localhost only (#29860)
dns agent: server should be served over localhost only (#29860)

Signed-off-by: Kailun Qin <0149305a169f8e13c8ed09a5bc4eb461ee5c4925@hotmail.com>
istio/istio,istio/istio,istio/istio,istio/istio,istio/istio