[polaris.shopify.com] Global search should be dismissed using `onKeyDown` to feel snappier

[martenbjork]

Dismissing the site search using onKeyDown will make it feel faster. However, we don't want to re-introduce this bug:

#6736

[github-actions]

Hi! We noticed there hasn’t been activity on this issue in a while. After 30 days, it will close automatically.

If it’s still relevant, or you have updates, comment and let us know. And don’t worry, you can always re-open later if needed.