Start separating authentication from connection to collab (#35471)

This pull request should be idempotent, but lays the groundwork for
avoiding to connect to collab in order to interact with AI features
provided by Zed.

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>
Co-authored-by: Richard Feldman <oss@rtfeldman.com>

crates/onboarding/src/ai_setup_page.rs

@@ -278,7 +278,7 @@ pub(crate) fn render_ai_setup_page(
                 .child(AiUpsellCard {
                     sign_in_status: SignInStatus::SignedIn,
                     sign_in: Arc::new(|_, _| {}),
-                    user_plan: onboarding.cloud_user_store.read(cx).plan(),
+                    user_plan: onboarding.user_store.read(cx).plan(),
                 })
                 .child(render_llm_provider_section(
                     onboarding,