This commit introduces a new configuration parameter 'event.event_mail_async'
forcing registrations-based communication to be asynchronous. Instead of
directly sending communication it triggers the cron to be run as soon as
possible.
When having large volume of registrations, and especially concurrent
registrations it saves a DB to avoid generating tickets and preparing emails
synchronously to the registration creation.
Task-3764894: Event: Allow using cron triggers for communication
Part of Task-3084943: Event: Improve communication scheduler scalability
Part-of: odoo/odoo#155777
Thibault Delavallée
793a42ff13