Bug 25266: Build the vendor list from the order list

Bug 25266: Build the vendor list from the order list

This patch is removing the use of GetBooksellersWithLateOrders and use
the late order list to generate the vendors.

Test plan:
Create several vendors, several orders, close the baskets
Also create vendors that do not have orders (or basket not closed)
Go to the late orders page and confirm that the list of vendors is
correctly filled, select one, you can see the "select all" link in the
header of the table

QA: that would be good to test this with production data and compare
execution time.

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Alex Arnaud <alex.arnaud@biblibre.com>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>