This fixes an automated barcode receipt test so it waits until the confirmation button is ready before proceeding. It helps prevent false test failures in the inventory barcode workflow, improving confidence in future updates without changing user-facing behavior.

The tour `test_gs1_receipt_lot_serial` tests we can manually write and confirm a barcode, but by checking that, it doesn't wait the "Apply" button is clickable (it's disabled if the input is empty).

runbot error id: 13671