[FIX] survey: set email_from on certification mail template
[FIX] survey: set email_from on certification mail template

Otherwise public users cannot receive their certification. Indeed email_from
will be the one of public user which is probably not set.

Task 2067872 (eLearning internal testing)
Task 2058598 (survey internal testing)
PR #36756
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo