[test] Fix test-object

See previous commit.
diff --git a/test/api/test-object.c b/test/api/test-object.c
index 4ea6f7c..02b9760 100644
--- a/test/api/test-object.c
+++ b/test/api/test-object.c
@@ -357,10 +357,6 @@
       g_assert (o->get_user_data (obj, &key[0]));
 
       o->destroy (obj);
-      o->destroy (obj);
-      o->destroy (obj);
-      o->destroy (obj);
-      o->destroy (obj);
 
       g_assert (data[0].freed);
     }