[FIX] product: variant sale price is wrong

If applied, this commit will fix the following bug by using the price
with the additional cost added instead of only the price

Steps to reproduce:

1- install sales
2- create a product p with variant pv
3- set an extra value for pv
4- go to Products>Product Variants
5- open the pv in form view
6- the Sales Price is the price of p not pv
(which should be p + extra value)
7- also the tax string is calculated on p not pv

Bug:

```list_price``` is being used

Fix:

replace ```list_price``` with  ```lst_price```

OPW-2774199

closes odoo#87248

Signed-off-by: William André (wan) <wan@odoo.com>

addons/account/models/product.py

@@ -63,24 +63,30 @@ def get_product_accounts(self, fiscal_pos=None):
     @api.depends('taxes_id', 'list_price')
     def _compute_tax_string(self):
         for record in self:
-            currency = record.currency_id
-            res = record.taxes_id.compute_all(record.list_price, product=record, partner=self.env['res.partner'])
-            joined = []
-            included = res['total_included']
-            if currency.compare_amounts(included, record.list_price):
-                joined.append(_('%s Incl. Taxes', format_amount(self.env, included, currency)))
-            excluded = res['total_excluded']
-            if currency.compare_amounts(excluded, record.list_price):
-                joined.append(_('%s Excl. Taxes', format_amount(self.env, excluded, currency)))
-            if joined:
-                record.tax_string = f"(= {', '.join(joined)})"
-            else:
-                record.tax_string = " "
+            record.tax_string = record._construct_tax_string(record.list_price)
+
+    def _construct_tax_string(self, price):
+        currency = self.currency_id
+        res = self.taxes_id.compute_all(price, product=self, partner=self.env['res.partner'])
+        joined = []
+        included = res['total_included']
+        if currency.compare_amounts(included, price):
+            joined.append(_('%s Incl. Taxes', format_amount(self.env, included, currency)))
+        excluded = res['total_excluded']
+        if currency.compare_amounts(excluded, price):
+            joined.append(_('%s Excl. Taxes', format_amount(self.env, excluded, currency)))
+        if joined:
+            tax_string = f"(= {', '.join(joined)})"
+        else:
+            tax_string = " "
+        return tax_string
 
 
 class ProductProduct(models.Model):
     _inherit = "product.product"
 
+    tax_string = fields.Char(compute='_compute_tax_string')
+
     def _get_product_accounts(self):
         return self.product_tmpl_id._get_product_accounts()
 
@@ -156,3 +162,8 @@ def _get_tax_included_unit_price(self, company, currency, document_date, documen
             product_price_unit = product_currency._convert(product_price_unit, currency, company, document_date)
 
         return product_price_unit
+
+    @api.depends('lst_price', 'product_tmpl_id', 'taxes_id')
+    def _compute_tax_string(self):
+        for record in self:
+            record.tax_string = record.product_tmpl_id._construct_tax_string(record.lst_price)

addons/product/views/product_views.xml

@@ -365,9 +365,10 @@
                 </xpath>
                 <field name="list_price" position="attributes">
                    <attribute name="attrs">{'readonly': [('product_variant_count', '&gt;', 1)]}</attribute>
+                   <attribute name="invisible">1</attribute>
                 </field>
                 <field name="list_price" position="after">
-                   <field name="lst_price" invisible="1"/>
+                   <field name="lst_price" class="oe_inline" widget='monetary' options="{'currency_field': 'currency_id', 'field_digits': True}"/>
                 </field>
                 <group name="packaging" position="attributes">
                     <attribute name="attrs">{'invisible': 0}</attribute>