[FIX] stock_account: always show update cost button on product
[FIX] stock_account: always show update cost button on product

With this commit, the 'update cost' button is always displayed on product.product
whatever the variant count

closes odoo/odoo#37328

Signed-off-by: Simon Lejeune (sle) <1969d8dff896674c2d819e813f5e88ca826229ab@openerp.com>

ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo