Fix octavia-dashboard py27/35 jobs
Fix octavia-dashboard py27/35 jobs

The py27/35 jobs for octavia-dashboard need to use the -horizon version
of the openstack-python-jobs.

Change-Id: I0d5f6a5bb238cafe0c8b5580b98a0b7b06c9b3eb

openstack-infra/project-config,openstack-infra/project-config