[FIX] mail: fix typo in attachment managment
[FIX] mail: fix typo in attachment managment

Fix some dead code. This is a fallback for linking mail attachment with
its data. The issue was not reported since a long time since this just
disable a fallback which in my tests was not used anyway.

opw-710502

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,hip-odoo/odoo,ygol/odoo,hip-odoo/odoo,ygol/odoo,ygol/odoo