[FIX] purchase_stock: vendor choice in multi-company

- Set two companies (A and B);
- Set intercompany flows enabled between company A and B with
  synchronization of PO/SO;
- create a product X is configured as follows in company B:
  -  Storable product;
  - Routes “Buy” and “Dropship”;
  - Vendors price list set with vendor = company A.
- Product X is configured as follows in company A:
  - Storable product;
  - Reordering rule Min 0 / Max 0;
  - Route “Buy”;
  - Vendors price list set with vendor = 'External Vendor'.
- Create and validate a sale order for product X to final customer
  within company B; Odoo will automatically create a purchase order for
  product X to company A within company B;
- Validate the purchase order in company B; Odoo will automatically
  create a sale order for product X to company B within company A;
- If there is no available stock in warehouse A; Odoo will automatically
  create a purchase order for product X within company A.

Before this commit, the purchase order is created with vendor as
'Company A'. As '_select_seller' is run in sudo mode (see:
https://github.com/odoo/odoo/blob/a16c4a0dabe58ab2cfade353c113387ae5bcd572/addons/stock/models/stock_rule.py#L458),
so is not company-aware, therefore the first matching supplier is
chosen.

Now, the purchase order will be created with vendor as 'External Vendor'.

opw-2255989

closes odoo/odoo#51596

closes odoo/odoo#51908

X-original-commit: e2dd8ea7544fba659810ba829433fce7099c1d40
Signed-off-by: Jorge Pinna Puissant (jpp) <jpp@odoo.com>

addons/purchase_stock/models/stock_rule.py

@@ -54,7 +54,7 @@ class StockRule(models.Model):
             if procurement.values.get('supplierinfo_id'):
                 supplier = procurement.values['supplierinfo_id']
             else:
-                supplier = procurement.product_id._select_seller(
+                supplier = procurement.product_id.with_company(procurement.company_id.id)._select_seller(
                     partner_id=procurement.values.get("supplierinfo_name"),
                     quantity=procurement.product_qty,
                     date=schedule_date.date(),