Bug 13418: Clean C4::VirtualShelves::Page a bit

Bug 13418: Clean C4::VirtualShelves::Page a bit

I tried to reuse this package for a new development, I did not manage.
It's a really hard to read and to understand.

Here my first try, this patch only remove the call to _shelf_count in
the GetShelves subroutine.
Someone might want to get this value for another reason and from
somewhere else.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>