Restore file to original content when rejecting file recreated by agent (#29264)

Release Notes:

- Fixed a bug that could sometimes cause a file to be deleted when
rejecting an agent change.

crates/assistant_tools/src/create_file_tool.rs

@@ -112,9 +112,12 @@ impl Tool for CreateFileTool {
                 .await
                 .map_err(|err| anyhow!("Unable to open buffer for {destination_path}: {err}"))?;
             cx.update(|cx| {
+                action_log.update(cx, |action_log, cx| {
+                    action_log.track_buffer(buffer.clone(), cx)
+                });
                 buffer.update(cx, |buffer, cx| buffer.set_text(contents, cx));
                 action_log.update(cx, |action_log, cx| {
-                    action_log.will_create_buffer(buffer.clone(), cx)
+                    action_log.buffer_edited(buffer.clone(), cx)
                 });
             })?;