revert: use timeout to determine scroll end

[yihuiliao]

Closes #8924

Reverts #8573, reverts everything except for the isScrolling

@nwidynski We've chosen to revert the above PR due to some issues with the native scrollend event not being fired in certain use cases. For now, this is the easiest fix but we do realize that the root problem hasn't been addressed

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

🧢 Your Project:

[nwidynski]

@yihuiliao Do you know which part of the code is responsible for scrolling the popover after deleting a collection element? I have a hunch the underlying issue could be due to the way we mutate scrollTop = <value> instead of calling scrollTo, which also caused other issues in the past (see #8715 (comment))

[yihuiliao]

@nwidynski Sorry for the late reply. I'm not entirely sure what is responsible for scrolling the popover when part of the input is deleted. I would have thought it was maybe scrollIntoView but it seems that doesn't get called which would be related to useSelectableCollection.

I'll continue to dig when I have time but I'm not the most familiar with the scroll position stuff unfortunately 😞