db: 0000_config.sql - update OvirtIsoPrefix

Update OvirtIsoPrefix to get iso name correctly during the
search for the iso in upstream and downstream.

Change-Id: I39ad1403b4afc8e6a5500c910560172395ee31fe
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1082612
Signed-off-by: Douglas Schilling Landgraf <dougsland@redhat.com>