Item tree: Expanding a row above the current selection causes expanded row to move up

https://github.com/user-attachments/assets/af53527d-f844-4d0b-b711-e516e67175dd

Works as expected when expanding a row at/below the selection, but when the expanded row is above, it moves up. If it's already at the top of the view, it moves offscreen.

I hadn't noticed this before the item tree refactor, but I'm not sure exactly when it was introduced.