[FIX] mail: do no try to send notification to inactive users
[FIX] mail: do no try to send notification to inactive users

- This commit prevent to send notifications to inactive users.
- This fixes a bug where two partners have been merged and one of its
  users is archived.

  If one of the two users is inactive the code might use its `notification
  type` preferences instead of the active user's one.

closes odoo/odoo#28730
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo