Sculpt: Fix disappearing object on undo

Tagging object for copy on write will ruin its PBVH.

Since sculpting is an "original" domain, we only need to
update draw batches to update.

source/blender/editors/sculpt_paint/sculpt_undo.c

@@ -493,7 +493,7 @@ static void sculpt_undo_restore_list(bContext *C, ListBase *lb)
 		}
 	}
 
-	DEG_id_tag_update(&ob->id, DEG_TAG_COPY_ON_WRITE);
+	DEG_id_tag_update(&ob->id, DEG_TAG_SHADING_UPDATE);
 
 	BKE_sculpt_update_mesh_elements(depsgraph, scene, sd, ob, false, need_mask);