[FIX] mrp: mrp_production.delivery_count more robust
[FIX] mrp: mrp_production.delivery_count more robust

when no group_id on mrp_production, set the delivery_count to 0

closes odoo/odoo#35372

Signed-off-by: Simon Lejeune (sle) <1969d8dff896674c2d819e813f5e88ca826229ab@openerp.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo