Shift more node use to HPCloud AZ2.

* modules/openstack_project/templates/nodepool/nodepool.yaml.erb: There
is more capacity available to us in HPCloud AZ2. Use that AZ more
heavily than AZ1 and AZ3 as a result.

Change-Id: Iae895ea0bbfc6b9f976a398d4e74de66e7ba0057