[FIX] purchase: default user_id on bill

On top of leading to AccessError in multi-company (if the PO was created
by OdooBot), it might also assign a user without Accounting rights to a
vendor bill.

This reverts commit 392f6f2b2b.

opw-2056061

closes odoo/odoo#36173

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/purchase/models/purchase.py

@@ -404,8 +404,6 @@ class PurchaseOrder(models.Model):
             'default_company_id': self.company_id.id,
             'company_id': self.company_id.id
         }
-        if self.user_id:
-            result['context']['default_user_id'] = self.user_id.id
         # choose the view_mode accordingly
         if len(self.invoice_ids) > 1 and not create_bill:
             result['domain'] = "[('id', 'in', " + str(self.invoice_ids.ids) + ")]"