Test edx-platform Django settings refactor PRs on a sandbox

[robrap]

Context:

There are about to be a number of setting refactor PRs that need to be tested to ensure they won't break edx.org.

The initial PR, openedx/edx-platform#36115, did break edx.org and we are looking to prevent that from recurring. It would be useful to check that this test process would have found that breakage.

Acceptance Criteria:

• Inform on [Attempt 2] refactor: Clean up lms/envs/production.py cruft openedx/edx-platform#36131 when the change has passed the test, or of any issues found.

Implementation Notes

• First, do a diff of settings configured in edx-internal. edge-internal, and sandbox-internal, and create a branch in sandbox-internal that sets all settings touched by prod and edge.
• The idea is simply to set up a sandbox and do a diff of dumps of the settings before and after a change.
  • This will use the PR under test as the codebase, and the test branch of sandbox-internal config created for these tests.
  • The current PR to test is: [Attempt 2] refactor: Clean up lms/envs/production.py cruft openedx/edx-platform#36131
• @kdmccormick is working on a management command to dump the settings.
• Consider extending the lifetime of the sandbox a little for re-use, or just rebuild as needed.
• Consider storing the settings some place (maybe not publicly), so we don't have to do the before-dump each time.
• See #openedx-cc-edx-platform Slack thread for more background, or from Open edX Slack, search for "Merged a settings refactoring" from Kyle.

[kdmccormick]

PR to add the dump_settings management command: openedx/edx-platform#36162