refine vmess test

testing/scenarios/vmess_test.go

@@ -270,8 +270,8 @@ func TestVMessGCM(t *testing.T) {
 	defer CloseAllServers(servers)
 
 	var wg sync.WaitGroup
-	wg.Add(10)
 	for i := 0; i < 10; i++ {
+		wg.Add(1)
 		go func() {
 			defer wg.Done()