agent_ui: Fix signed-in check in Zed provider configuration (#36639)
Marshall Bowers
created
This PR fixes the check for if the user is signed in in the Agent panel
configuration.
Supersedes https://github.com/zed-industries/zed/pull/36634.
Release Notes:
- Fixed the user's plan badge near the Zed provider in the Agent panel
not showing despite being signed in.