Revert "ClassDB: Workaround double-free for GDScript"

This reverts commit 8312ead0d99cfc308f2f7635bae3da6bf0ff5489.

core/class_db.cpp

@@ -1410,10 +1410,7 @@ Variant ClassDB::class_get_default_property_value(const StringName &p_class, con
 			cleanup_c = false;
 		} else if (ClassDB::can_instance(p_class)) {
 			c = ClassDB::instance(p_class);
-#ifndef _MSC_VER
-#warning FIXME: ObjectID refactoring broke GDScript handling of reference pointers, this needs a proper fix.
-#endif
-			cleanup_c = (p_class != StringName("GDScript"));
+			cleanup_c = true;
 		}
 
 		if (c) {