eval: Don't read the model from the user settings (#31230)

This PR fixes an issue where the eval was incorrectly pulling the
provider/model from the user settings, which could cause problems when
running certain evals.

Was introduced in #30168 due to the restructuring after the removal of
the `assistant` crate.

Release Notes:

- N/A

crates/eval/src/eval.rs

@@ -432,6 +432,7 @@ pub fn init(cx: &mut App) -> Arc<AgentAppState> {
         client.clone(),
         prompt_builder.clone(),
         languages.clone(),
+        true,
         cx,
     );
     assistant_tools::init(client.http_client(), cx);