Force instant scrolling in scroll restoration

[david-bezero]

Currently if a page uses ScrollRestoration and has the following CSS:

html {
  scroll-behavior: smooth
}

then the page will appear to jump around in a non-intuitive way when switching to a new page (specifically: it will show the current scroll position on the new page, then animate to the correct scroll position). Having this global smooth scrolling behaviour can be desirable in some cases (e.g. within large pages with internal anchor links), but is never desirable when switching between pages.

I propose changing ScrollRestoration to force immediate scrolling (see #10318 for details)

On that PR, it was suggested that an alternative approach might be to make the scrollTo function into customisable parameter. This would also enable solving the issue, but since the default behaviour would continue to be surprising in this scenario, it puts the burden on every user individually to fix it.