engine: Wrong vnic profiles on vm based on template from another cluster

If-
1. New vm is based on template from different cluster (or even dc in
case of 'Blank' template).
And
2. The template has nics which's profile's network is not attached to the
vm's cluster.

Then-
The profiles on the vm's nics should be overridden by 'Empty' profiles.

Change-Id: I678c8db0e56c9ba9e9e947028d14ae4ddae76e0a
Bug-Url: https://bugzilla.redhat.com/1103058
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>