095cd1985e
Set the image build jobs to use the nodepool labels rather than the nodeset definitions. This will allow us to switch nodeset definitions back and forth between nodepool and niz easily and quickly, without incurring the penalty of image builds. Once we're further to the other side of the transition, we can remove this and let the image builds use nodeset definitions. Change-Id: I026df4d47a7a79d910d158fb0e8b8ceeb0045fd0