Fix error test case for emqx

test/emqx_SUITE.erl

@@ -45,7 +45,6 @@ t_stop_start(_) ->
     false = emqx:is_running(node()).
 
 t_get_env(_) ->
-    emqx:start(),
     ?assertEqual(undefined, emqx:get_env(undefined_key)),
     ?assertEqual(default_value, emqx:get_env(undefined_key, default_value)),
     application:set_env(emqx, undefined_key, hello),
@@ -54,6 +53,7 @@ t_get_env(_) ->
     application:unset_env(emqx, undefined_key).
 
 t_emqx_pubsub_api(_) ->
+    emqx:start(),
     true = emqx:is_running(node()),
     {ok, C} = emqtt:start_link([{host, "localhost"}, {clientid, "myclient"}]),
     {ok, _} = emqtt:connect(C),