Ensure packages for octavia only when EnablePackageInstall is True
Ensure packages for octavia only when EnablePackageInstall is True

Changing the ansible task for ensuring packages to run only when
EnablePackageInstall is True.
Also removed the step4 tag from this task as there are no tags
in host_prep_tasks.

Change-Id: I1374b20ec66694fe661183e089f8d88473be11a9

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates,dprince/tripleo-heat-templates,dprince/tripleo-heat-templates