Improve speed of products by quantities
When opening a location to the list of products, there is a domain to show only product with at least quantity or forecast quantity not null. This was added by #939 (closed).
The problem is that the implementation of the searcher needs to compute the quantities for all the products (see #6605 (closed)). So on database with a lot of products, this can become a serious bottleneck because it is O(l * p) (l=number of location and p number of product).
I think that it is not really needed to filter by quantities for this view and instead we can just filter product of type service.
We have a similar filter on location when opening a product. But I think we can keep it because the number of locations is limited and in case of very large number flat locations will be used (and it is of O(l)).