It's not, just Google's abandoned interface to it. You can still access it via a Usenet client:
formatting link
There are also a few web frontends, eg:
formatting link
No experience with Fiestas or their steering racks, but when I search ebay for Mk5 racks it seems to suggest Mk6 racks will fit Mk5 2005-2010, eg:
formatting link
which the ebay compatibility checker says will fit back to 2001. I wouldn't
100% trust ebay's idea of fitment but it does suggest they might.
Maybe you can squint at the pictures and try to work out if they can be taken apart to replace bit by bit. From this one it suggests it's a single piece:
formatting link
If you search Youtube there are a variety of videos on fixing fluid leaks on the Mk6 - if the rack is the same maybe they also apply to the Mk5?
Theo