Update ProductSale.php

Fixed an issue how the way we are retrieving Best Sellers. In case you would have a category which is in ps_category_group (100% of your categories usually) but not in ps_category_product (no products inside this category), the IDs list would be corrupted (eg. ",1,2,3" instead of "1,2,3").
// again moving scripts in bootstrap template +  disable instantsearch temporarly