AMQP 0.9: Send the connection.open_ok after all init

This is an attempt to solve flakes WIP

deps/rabbit/src/rabbit_reader.erl

@@ -1252,7 +1252,6 @@ handle_method0(#'connection.open'{virtual_host = VHost},
     ok = rabbit_access_control:check_vhost_access(User, VHost, {socket, Sock}, #{}),
     ok = is_vhost_alive(VHost, User),
     NewConnection = Connection#connection{vhost = VHost},
-    ok = send_on_channel0(Sock, #'connection.open_ok'{}, Protocol),
 
     Alarms = rabbit_alarm:register(self(), {?MODULE, conserve_resources, []}),
     BlockedBy = sets:from_list([{resource, Alarm} || Alarm <- Alarms]),
@@ -1276,6 +1275,9 @@ handle_method0(#'connection.open'{virtual_host = VHost},
     rabbit_log_connection:info(
       "connection ~ts: user '~ts' authenticated and granted access to vhost '~ts'",
       [dynamic_connection_name(ConnName), Username, VHost]),
+
+    ok = send_on_channel0(Sock, #'connection.open_ok'{}, Protocol),
+
     State1;
 handle_method0(#'connection.close'{}, State) when ?IS_RUNNING(State) ->
     lists:foreach(fun rabbit_channel:shutdown/1, all_channels()),