Update CI versions & cleanup setup scripts

[AndrewFasano]

Supersedes @AndrewQuijano's #1514. I want to test if CI behaves differently when issued from a member of the panda-re org.

I dropped the CI changes around org-wide secrets and cache images on dockerhub instead of github infrastructure because it didn't seem to make a difference when external folks open PRs. So we may as well stick with what has been working.

[AndrewQuijano]

Nice! It worked! I guess once the workflow_dispatch is there, we can see if clicking a different button might allow running parallel tests for external works.

https://stackoverflow.com/questions/69499645/how-to-securely-allow-github-actions-to-check-pr-and-post-results-in-comment