Better fix for a Dialyzer warning

The previous fix was leading to a badmatch in some cases,
including when trying to stop a node that was already stopped.

Author: lhoguin

deps/rabbitmq_ct_helpers/src/rabbit_ct_broker_helpers.erl

@@ -1134,7 +1134,7 @@ stop_rabbitmq_node(Config, NodeConfig) ->
       {"RABBITMQ_NODENAME_FOR_PATHS=~ts", [InitialNodename]}
     ],
     Cmd = ["stop-node" | MakeVars],
-    {ok, _} = case rabbit_ct_helpers:get_config(Config, rabbitmq_run_cmd) of
+    _ = case rabbit_ct_helpers:get_config(Config, rabbitmq_run_cmd) of
         undefined ->
             rabbit_ct_helpers:make(Config, SrcDir, Cmd);
         RunCmd ->