Currently, the Grid Row Pool only expands. If a user increases bufferRowRange (creating many rows) and then decreases it, the excess rows remain in memory and the VDOM tree, causing permanent performance degradation.

This task implements "Self-Healing" in createRowPool:

• When needed < current, destroy excess Row instances.
• Update items and vdom.cn.
• Restore optimal performance after buffer reduction.

This complements the fixes in #9168.