test-runner: fix double free issue on subtest queue

Coverity reported this as a leak, but the test queue is actually
getting freed later and does not need to be freed locally in add_path

This basically reverts c0863e5bc6

tools/test-runner.c

@@ -1092,8 +1092,6 @@ static bool add_path(const char *path, int level, struct l_queue *config_queue)
 		l_queue_insert(config_queue, entry, insert_test_entry, NULL);
 	}
 
-	l_queue_destroy(py_test_queue, l_free);
-
 	closedir(dir);
 	return true;
 }