Show "Restore Checkpoint" only when there were changes (#27243)

Release Notes:

- N/A

---------

Co-authored-by: Agus Zubiaga <hi@aguz.me>
Co-authored-by: Bennet Bo Fenner <bennetbo@gmx.de>
Co-authored-by: Danilo Leal <daniloleal09@gmail.com>

crates/assistant_eval/src/eval.rs

@@ -96,7 +96,7 @@ impl Eval {
             assistant.update(cx, |assistant, cx| {
                 assistant.thread.update(cx, |thread, cx| {
                     let context = vec![];
-                    thread.insert_user_message(self.user_prompt.clone(), context, None, cx);
+                    thread.insert_user_message(self.user_prompt.clone(), context, cx);
                     thread.set_system_prompt_context(system_prompt_context);
                     thread.send_to_model(model, RequestKind::Chat, cx);
                 });