Cleanup zuul.yaml
Cleanup zuul.yaml

Small cleanups:
* Sort templates
* Use python35/python36 horizon templates and remove
  included jobs

Change-Id: I2d5b64653b49f1efcaecfb46c56d549aeba7f9d4

openstack/trove-dashboard,openstack/trove-dashboard,openstack/trove-dashboard,openstack/trove-dashboard