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/zed/src/main.rs

@@ -519,6 +519,7 @@ fn main() {
             app_state.client.clone(),
             prompt_builder.clone(),
             app_state.languages.clone(),
+            false,
             cx,
         );
         assistant_tools::init(app_state.client.http_client(), cx);

crates/zed/src/zed.rs

@@ -4295,6 +4295,7 @@ mod tests {
                 app_state.client.clone(),
                 prompt_builder.clone(),
                 app_state.languages.clone(),
+                false,
                 cx,
             );
             repl::init(app_state.fs.clone(), cx);