Properly update parent item's bounding rect when moving item

The bounding rect of an item is in the item-local coordinate space. If
the item is moved, its bounding rect won't change, but the parent's
bounding rect, may change.

BUG: 443756


(cherry picked from commit 59a4a908)

src/item.cpp

@@ -106,7 +106,9 @@ void Item::setPosition(const QPoint &point)
     if (m_position != point) {
         scheduleRepaint(boundingRect());
         m_position = point;
-        updateBoundingRect();
+        if (m_parentItem) {
+            m_parentItem->updateBoundingRect();
+        }
         scheduleRepaint(boundingRect());
         Q_EMIT positionChanged();
     }