Clean up testing/contributing

[jasonb5]

Description

• Cleans up contribute-guide.rst.
• Cleans up CONTRIBUTING.md.
• Removes scripts_regression_tests.py, replaced by pytest.
• Remove old code_checker.py, replaced by pylint via pre-commit.

---

• Closes Testing instructions in CONTRIBUTING.md are incorrect/incomplete #4936

Checklist

• My code follows the style guidelines of this project (black formatting)
• I have performed a self-review of my own code
• My changes generate no new warnings
• I have added tests that exercise my feature/fix and existing tests continue to pass
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding additions and changes to the documentation

[github-actions]

You can preview documentation at https://esmci.github.io/cime/branch/remove-scripts-regression/html/index.html

[billsacks]

Thanks a lot for this cleanup!

[samsrabin]

@billsacks Were you able to get the container to work? I tried on Casper with podman, and it just stopped after a bunch of "Copying blob ... Done" messages.

podman run -it --rm --hostname docker -e CIME_MODEL=cesm -v $PWD:/root/model -v ./storage:/root/storage -w /root/model/cime ghcr.io/esmci/cime:latest bash

[billsacks]

Were you able to get the container to work?

No, I haven't tried it yet.