Disable uncompressed images for tripleo-cd.
Disable uncompressed images for tripleo-cd.

We're out of space on the undercloud, and we still can't redeploy that
so this is a workaround...

Change-Id: Ic86d3cf19525c78f9e350537ca09a71d589b0975

openstack/tripleo-image-elements,radez/tripleo-image-elements,radez/tripleo-image-elements,rdo-management/tripleo-image-elements,openstack/tripleo-image-elements,rdo-management/tripleo-image-elements