[FW][FIX] mail: correctly avoid increasing bounced counter two times

When a bounce has to be managed on a record already inheriting from blacklist
mixin it shoudl not be counted two times: one for email-based bounce and one
for "all records using that email linked to blacklist mechanism should
bounce".

A mechanism exists to prevent that double increase but it was not correctly
done. Protection was reset in a loop.

Task ID-2547347
PR odoo/odoo#72347

closes odoo/odoo#72420

X-original-commit: 6e1bca5d
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>