[install] Update ec2authtoken version suffix
[install] Update ec2authtoken version suffix

Updated ec2authtoken auth_uri in heat.conf with
v3 suffix.  This is required if one wants to utilize
autoscaling in heat.

Change-Id: I06a498bce261ed6929476d12d04d7eaaf6df96b0
Closes-Bug: 1588111

AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,AlekhyaMallina-Vedams/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals