UI papercut: search sidebar has different hover state animations

Created by: quinnkeast

On the search sidebar, different items have different animations for showing the hover state. This makes it feel inconsistent.

Quick Loom recording as a demo: https://cln.sh/xO7bua

I previously talked in Slack about removing css transitions everywhere, but haven't made an explicit issue for it yet. Would it be better to address this as a standalone issue, or make the unifying issue to address it everywhere?