Clean up unused workflows

[enyst]

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

• Include this change in the Release Notes. If checked, you must provide an end-user friendly description for your change below

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Give a summary of what the PR does, explaining any non-trivial design decisions

This PR proposes to:

• disable the nightly schedule on the eval-this workflow. It isn't working, but it does try to run 20k lines of log worth of attempts, using the remote runtime - example
• remove the old PR review workflow.

I'm not sure about the removal of the PR review workflow... I think that since it isn't working right now, it needs a bit of looking into, but it seems like it would be better to fix it based on the resolver rather than a custom main.py run, as it used to be implemented. That probably means this won't be reused and we can look at building it on the resolver. If you feel like it's still useful, let's keep it for now though...

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Link of any specific issues this addresses
Related to #5106

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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:d7ee8d3-nikolaik   --name openhands-app-d7ee8d3   docker.all-hands.dev/all-hands-ai/openhands:d7ee8d3

[neubig]

Sounds good to me!