reduce the amount of list items rendered simultaneously

[kaitoo1]

Summary of Changes

We currently render about 10-12 items in the virtualized feed at any given moment on web. Since we live render pieces, this creates a big burden on the browser if there are a lot of generative pieces on the feed. We're currently rendering ~10 rows total that aren't visible above or below the screen edge via the overscanRowCount prop, so this PR reduces it to 2 above and below.
This means we only render 2 rows above and 2 rows below what's currently visible, drastically reducing the number of invisible items we display.

Demo or Before/After Pics

• If this is a new feature, include screenshots or recordings of the feature in action.
• If this PR makes visual changes, include before and after screenshots.

Before	After

video, before

CleanShot.2023-10-04.at.20.27.00.mp4

video, after

CleanShot.2023-10-04.at.20.31.44.mp4

Edge Cases

Looked at different pages with feeds

Testing Steps

go scroll anywhere that uses the FeedList component and verify the scrolling behavior seems normal

Checklist

Please make sure to review and check all of the following:

• I've tested the changes and all tests pass.
• (if web) I've tested the changes on various desktop screen sizes to ensure responsiveness.
• (if mobile) I've tested the changes on both light and dark modes.

[vercel]

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Name	Status	Preview	Updated (UTC)
gallery	✅ Ready (Inspect)	Visit Preview	Oct 4, 2023 0:06am

[github-actions]

Bundle Sizes

Compared against 5ebd2a5

Route: No significant changes found

Dynamic import: No significant changes found