[FIX] stock: backorder pickings
[FIX] stock: backorder pickings

With the demo data:
- Go to Inventory
- On the 'Delivery Order' Kanban card of YourCompany, click on 'Back Orders'

More pickings are displayed than the expected count.

This is because the domain of the filter is not in line with the domain
of `_compute_picking_count`.

closes odoo/odoo#33953

Signed-off-by: Nicolas Martinelli (nim) <771435c469f83f6aa9c405ac5e1ed06314a94f2d@odoo.com>
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo