Delete an avatar video

Cancels the job if it is still running, then deletes its recording, session report and job content. Returns 200 once everything is deleted, or 202 when Lab finishes the deletion in the background, either because the session is still ending or because a delete failed and will be retried. Background deletion runs every minute and keeps retrying until it succeeds. The job row stays, without content, and a retry returns 409 content_expired. Repeating the call is safe.