Move {name}-publish-specs job + others to ubuntu-xenial
Move {name}-publish-specs job + others to ubuntu-xenial

This commit moves all the specs-jobs to xenial. Previously this job as done
on trusty.

Change-Id: I461edff862e1bcda1d49dfce27efb12790484cbe

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