Updated the existing prompts

[tangxiangru]

Updated the existing prompts for billsum, pubmed_qa, and scientific_papers(arxiv).

[stephenbach]

Thanks @tangxiangru. Can you look into why the tests are failing? It looks like at least one template doesn't parse.

[VictorSanh]

It would be also worth adding the metrics in the same pass!

[VictorSanh]

thanks for working on this @tangxiangru!
i pushed a few minor changes
the test show_new_templates is failing because the combination of 3 datasets is fairly big so there is not enough space on the CI device, but I ran the test locally and they work fine
merging now.