Do not copy accounting templates when copying product category for accounting

Closes #14862
(grafted from 6cd898bfdb36da8c69ecaa9ca85eb07b4cc88df3)

--HG--
branch : 7.0

modules/account_product/product.py

@@ -252,6 +252,12 @@ class Category(CompanyMultiValueMixin, metaclass=PoolMeta):
         else:
             return self.supplier_taxes_deductible_rate
 
+    @classmethod
+    def copy(cls, categories, default=None):
+        default = default.copy() if default is not None else {}
+        default.setdefault('accounting_templates')
+        return super().copy(categories, default=default)
+
 
 class CategoryAccount(ModelSQL, CompanyValueMixin):
     "Category Account"