[action required] Plugins should use django's new STORAGE config for 3.70

[pedro-psb]

Does this apply to me?

Some work has been done in pulpcore. Still, some action is required and some may be required.

Requried:

1. Configure CI to exercises the new STORAGES in at least 1 scenario (e.g, S3). Some scenario should still keep the legacy. Reason: both should be supported for the period [3.70, 3.85). Must happen on the PR declaring 3.70 compatibility.

Conditionally required: edit: Only pulp_container and pulp_ansible required some. PRs are open.

2. If plugin uses settings.DEFAULT_FILE_STORAGE or settings.STATICFILE_STORAGE explicitly, replace legacy with new.
3. If plugin uses settings imported globally on AppConfig ({plugin}/app/__init__.py) and uses that on signal handlers, move that to in-class.

For more context: https://github.com/pulp/pulpcore/issues/5404

How to do it?

For the respective cases:
1. Edit the .ci/ansible/settings.py.j2 file (dont apply anymore)

1. Edit ./template_config.yml and apply plugin-template (example after plugin-template applied)
2. Replace occurrences of the legacy config:

   -settings.DEFAULT_FILE_STORAGE
   +settings.STORAGES["default"]["BACKEND"]
   
   -settings.STATICFILES_STORAGE
   +settings.STORAGES["staticfiles"]["BACKEND"]
   

3. Move the settings import from module-level to class-level (instantiation time)
   • Example commit with required changes on app/apps.py

When should this happen?

• 1: On the PR declaring 3.70 compatibility.
• 2 and 3: Before or on the PR declaring 3.70 core compatibility.

[pedro-psb]

Issues tracking (this is editable by anyone):

• [x] pulpcore
• [ ] pulp_ansible
• [ ] pulp_container
• [ ] pulp_debian
• [x] pulp_gem
• [x] pulp_maven
• [x] pulp_python
• [x] pulp_ostree
• [ ] pulp_rpm

[pedro-psb]

Step 1 procedure was updated to use plugin-template.
Do this when when declaring compat with core 3.70.