Update summary_prompt for improved code quality

[neubig]

• This change is worth documenting at https://docs.all-hands.dev/
• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

End-user friendly description of the problem this fixes or functionality this introduces.

Increase code quality of resulting resolver PRs by adding slightly more extensive checks that the PR is correct and concise.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:d61dfbf-nikolaik   --name openhands-app-d61dfbf   docker.all-hands.dev/all-hands-ai/openhands:d61dfbf

[malhotra5]

Thanks! The prompt looks much better 🤩

[jpelletier1]

I wonder if this prompt will help address this feedback, too: #8926