ModalDialog does not scroll into view on Chromium

The ModalDialog is expected to display in the centre of the viewport when open. In Firefox, this works fine: the modal is displayed overlaid over the centre of the page and the page is scrolled into view so the modal is in the centre of the viewport:

However, in Chromium, it displays in the centre of the page, but it does not scroll into view. So if you are on a long page (eg. a unit with several components), and currently at the top or bottom of the page, the Modal appears off-screen, resulting in an unfriendly darkened page:

The modal is visible if you manually scroll up, but this is not great UX.

To reproduce

• create a unit with several components
• for the first or last component, ensure it is one that lets you trigger a ModalDialog (not sure what else uses this; we're adding them to https://github.com/open-craft/xblock-ai-evaluation currently, which is a work in progress)
• publish and view as a learner in Firefox
• scroll up or down to the component, and trigger the modal
• verify that the modal displays in the centre of the viewport
• open the same page in Chromium and repeat triggering the modal
• verify that the modal displays out of the viewport

Paragon version: @openedx/paragon@23.21.2

Start at the ModalDialog component and reproduce the issue using the steps in the report, comparing Firefox with Chromium on a long page. Done means opening the modal from a first or last component brings it into the centre of the Chromium viewport as it does in Firefox.