Disable stackviz on xenial for now
Disable stackviz on xenial for now

npm install throws 502 errors randomly, we cannot properly build xenial
images. Disable stackviz for now on Xenial until npm is fixed.

Change-Id: Id3b9644d6790ad8dbe62f2d373e073a227515cf5

openstack-infra/project-config,dongwenjuan/project-config,Tesora/tesora-project-config,dongwenjuan/project-config,openstack-infra/project-config,Tesora/tesora-project-config