message: add the plugin for peer discovery
diff: @@ -2,7 +2,8 @@ FROM rabbitmq:3-management
  COPY rabbitmq_delayed_message_exchange-3.7.0.ez /plugins
  -RUN rabbitmq-plugins enable --offline rabbitmq_delayed_message_exchange
  +RUN rabbitmq-plugins enable --offline rabbitmq_delayed_message_exchange; \
  + rabbitmq-plugins --offline enable rabbitmq_peer_discovery_k8s
  ENV RABBITMQ_DEFAULT_USER=guest \
  RABBITMQ_DEFAULT_PASS="guest" \
  