feat: add enterprise group deletion event

[jesperhodge]

Testing Instructions

• Have event bus running locally. Not set up? Easiest to have me screen share.
• If you have the event bus up, pip install -e this into a repo where it can be used and where event bus is configured correctly, and then run this: (if the repo is lms, change command to run python2 manage.py lms produce_event ... instead)
• python3 manage.py produce_event --signal openedx_events.enterprise.signals.ENTERPRISE_GROUP_DELETED \ --topic enterprise-core --key-field enterprise_group.uuid \ --data '{"enterprise_group": { "uuid": "d509a63b-eb11-4dc8-8b84-4688c7335110" }}'
• Verify that message in event bus is created.

Description

If a budget Group is manually deleted (e.g. through django admin), but the PolicyGroupAssociation is not, we end up in a weird state where the budget is looking for a group that doesn’t exist anymore. We should automatically trigger a delete of any PolicyGroupAssociations with the same group ID whenever a budget Group is deleted.

The plan is to

• Utilize openedx-events with kafka to send an async event from edx-enterprise to our event broker
• Create a consumer on enterprise-access consume this event and delete the corresponding PolicyGroupAssociation

Internal 2U ticket: https://2u-internal.atlassian.net/browse/ENT-10440
Edx-enterprise Producer PR: openedx/edx-enterprise#2413

Checklists

Check off if complete or not applicable:

Merge Checklist:

• All reviewers approved
• Reviewer tested the code following the testing instructions
• CI build is green
• Version bumped
• Changelog record added with short description of the change and current date
• Documentation updated (not only docstrings)
• Integration with other services reviewed
• Fixup commits are squashed away
• Unit tests added/updated
• Noted any: Concerns, dependencies, migration issues, deadlines, tickets

Post Merge:

• Create a tag
• Create a release on GitHub
• Check new version is pushed to PyPI after tag-triggered build is
  finished.
• Delete working branch (if not needed anymore)
• Upgrade the package in the Open edX platform requirements (if applicable)

[mariajgrimaldi]

Hi there! Is this ready for review? Let me know. Thanks!

[jesperhodge]

Hi @mariajgrimaldi ! Thanks for the patience, I was out of office a lot the last weeks. The PR is ready for review, let me know if you have any questions.