Speed up Visual Studio update installation

We have a prepared package on the internal server that has everything
necessary included. This way we do not have to download the actual
update content from the internet.

Change-Id: Ie4cb3116a4f91a47df5be1c2b2e473d7ddec9a78
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
Reviewed-by: Aapo Keskimolo <aapo.keskimolo@qt.io>