Fix eval judging missing final response (#29638)

Fixed issue where eval thread judges were not considering the last
response in the thread.

The problem was that they were getting the full list of messages from
`last_request`, which (being a request!) did not have the response yet.

Release Notes:

- N/A
c8685dc90fRichard Feldman committed on 4/30/2025, 3:02:46 AM· committed by GitHubparentd566864
2 files changedLine totals unavailable