Only register the first web-dispatch listener

The problem: on certain double IPv4 and IPv6 environments, web-dispatch
will start a single listener (for management for example) but will
register two listeners in the Rabbit Mnesia table. Later, RabbitMQ
will crash when trying to stop or suspend them (rabbitmq-upgrade drain)
because only one of the two listeners exist in Ranch.

The fix: we register only the first listener, because that's the one
we used to create the Ranch ref (see rabbit_networking:ranch_ref/1).

deps/rabbitmq_web_dispatch/src/rabbit_web_dispatch_registry.erl

@@ -157,9 +157,9 @@ listener_info(Listener) ->
                        P
                end,
     Port = pget(port, Listener),
-    [{Protocol, IPAddress, Port}
-     || {IPAddress, _Port, _Family}
-        <- rabbit_networking:tcp_listener_addresses(Port)].
+    [{IPAddress, _Port, _Family} | _]
+        = rabbit_networking:tcp_listener_addresses(Port),
+    [{Protocol, IPAddress, Port}].
 
 lookup_dispatch(Lsnr) ->
     case ets:lookup(?ETS, pget(port, Lsnr)) of