Rename tripleo-centos-7-ovb to tripleo-centos-7
Rename tripleo-centos-7-ovb to tripleo-centos-7

This is a cosmetic change for nodepool, since this image still only
runs on tripleo-test-cloud-rh1, we need the prefix still.

We'll do this over a series of commits as to not affect running jobs.

Change-Id: Ife98111740232791467523a7f5dd22307b096b1e
Signed-off-by: Paul Belanger <e7139c8e6c4ea75cc1c287ce081b2dc0f3ab39ec@redhat.com>

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