[next] Scrollbar flickering while dragging a card in a kanban board

Hi, I was checking out the new dnd-kit storybook examples. I noticed an issue where the scrollbar flickers while dragging a card.

Here's a video reproducing the issue. From this [link](https://experimental--5fc05e08a4a65d0021ae0bf2.chromatic.com/?path=/story/react-sortable-multiple-lists--scrollable)

https://github.com/user-attachments/assets/a104342e-3d6a-4e61-9260-85ddc79d52f9

I was testing it for a side project, Amazing library btw! Thanks!

Start by reproducing the issue in the linked Storybook example, react-sortable-multiple-lists--scrollable, while dragging a card. Inspect the relevant drag-and-drop and scroll behavior around that example. Done means the scrollbar no longer flickers during a card drag and the example still behaves correctly.

Written by the indexing model from the issue text.