[FIX] event: prevent scheduled communication for inactive events
Prior this commit:
The mail scheduler of the event notifies the attendees even when the event is
no longer active.
After this commit:
Inactive events no longer notify attendees.
Task-3381876
closes odoo/odoo#130237
Signed-off-by:
Thibault Delavallee (tde) <tde@openerp.com>