🐛 [BUG] - Issues with River Story Scroll on mobile breakpoint

[joshvogel17]

Describe the bug

This was noticed in production with RiverStoryScroll disabled, but in a mobile view. There are two issues:

1. RiverStoryScroll does not appear to disabled at the mobile breakpoint.
2. River components are overlapping each other.

Here is a short video from production to illustrate.
https://github.com/user-attachments/assets/c79e4fd4-b9eb-473b-b898-2bc41e4aeb72

Reproduction steps

1. On branch of Dotcom add `RiverStoryScroll` around Rivers in `ui/packages/solutions/routes/Detail/Detail.tsx`
2. Start server with command `script/server`
3. Go to http://github.localhost/solutions/use-case/devops?_features=contentful_lp_solution_pages on desktop.
4. Scroll down page to River Components.
5. Notice that `RiverStoryScroll` is disabled.
6. Change to mobile view
7.  Scroll down page to River section
8. Notice `RiverStoryScroll` is enabled and the River Components are overlapping each other.

Expected behavior

If `RiverStoryScroll` is disabled, then the Rivers should not have the RiverStoryScroll behavior in mobile view. If it is enabled, `River` components should not stack on top of each other.

Screenshots

Browsers

Chrome, Firefox, Safari

OS

No response

[stamat]

Original Story Scroll removal PR here: https://github.com/github/github/pull/356869

[joshvogel17]

Original Story Scroll removal PR here: github/github#356869

Sorry, I'll update my repro steps. It was decided to remove from production.