[FIX] sale: translate product description

Issue:
In a multi-language environment, the product description in sales
orders defaults to English, regardless of the user's language
preference. This issue occurs when the language of the partner
is not set, leading to a mismatch between the user's expected language
and the displayed language for product descriptions.

Steps to Reproduce:
1. Ensure the database supports multiple languages.
2. Set the user's preferred language to a non-English language.
3. Create a new sale order for a partner whose language is not set.
4. Add a product and observe that its description is displayed in
    English instead of the user's preferred language.

Solution:
Modified the logic to default the product description to the user's
language preference when the partner's language is not specified.

opw-3586451

closes odoo#142227

X-original-commit: 29ace25
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>
Signed-off-by: Kawtar Drissi El Bouzaidi (kdeb) <kdeb@odoo.com>

addons/sale/models/sale_order_line.py

@@ -313,13 +313,14 @@ def _compute_no_variant_attribute_values(self):
     @api.depends('product_id')
     def _compute_name(self):
         for line in self:
+            lang = line.order_partner_id.lang or self.env.user.lang
             if not line.product_id:
                 continue
             if not line.order_partner_id.is_public:
-                line = line.with_context(lang=line.order_partner_id.lang)
+                line = line.with_context(lang=lang)
             name = line._get_sale_order_line_multiline_description_sale()
             if line.is_downpayment and not line.display_type:
-                context = {'lang': line.order_partner_id.lang}
+                context = {'lang': lang}
                 dp_state = line._get_downpayment_state()
                 if dp_state == 'draft':
                     name = _("%(line_description)s (Draft)", line_description=name)