[FIX] sale_management: fix quotation template orderline price

Reproduce the issue

    - Install Sale
    - Create a quotation template with a product price that is different
      than the price on the product form.
    - Create a quotation
    - Select a customer then the quotation template

    The product price is not the price mentionned in the quotation
    template

Cause

    In the method `onchange_sale_order_template_id`, if we have
    a pricelist set and the discount policy "with discount" we
    use the price of the pricelist instead of the price of the
    template line.

This commit use the template line's price if the discount policy
is not 'without' discount and if there is a template line's price

OPW-2146210

closes odoo/odoo#41139

X-original-commit: 1ed2c4dc
Signed-off-by: Victor Feyens (vfe) <vfe@odoo.com>

addons/sale_management/models/sale_order.py

@@ -84,6 +84,8 @@ class SaleOrder(models.Model):
                             discount = 0
                         else:
                             price = line.price_unit
+                    elif line.price_unit:
+                        price = line.price_unit
 
                 else:
                     price = line.price_unit