Soa metared

[ccantillo]

Description

This PR hooks into the Open edX user retirement pipeline to permanently delete the user after the retirement steps complete, enabling email reuse per MetaRed policy.

Changes included:

• Adds EoxCoreConfig.ready() to import eox_core.handlers and register signal receivers.
• Adds a signal handler for USER_RETIRE_LMS_MISC that schedules a Celery task with a short delay to avoid race conditions while the pipeline is still saving the user.
• Adds delete_user_task Celery task (with retries) that deletes the user by id and logs success/failures.

Additional information

• Uses the retirement signal step USER_RETIRE_LMS_MISC and performs deletion asynchronously to avoid conflicts with the sender still persisting the user instance.
• Task retries up to 3 times with a short delay and handles “already deleted” safely.
• Queue/routing is explicitly set to edx.lms.core.default.