Specify nodeset for dlrn-puppet-* jobs
Specify nodeset for dlrn-puppet-* jobs

The rdo-centos-7 nodeset may or may not be present in the Zuul
configuration.

Change-Id: Ia61450028161e4e684069fca1f327e7af4df920e

javierpena/puppet-delorean,rdo-infra/puppet-dlrn,rdo-infra/puppet-dlrn,javierpena/puppet-delorean,javierpena/puppet-delorean,rdo-infra/puppet-dlrn