The stack-create operation fails. The current implementation of
Heat Ansible role does not implement trusts. Tell heat it should use
the non-trusts authentication model.
Also add a [keystone_clients] section which is required in newer
versions of heat to properly resolve the keystone v3 API endpoint
required for trust communication.
This fix spawns a Tech-Debt Bug to implement trusts in heat: #1492736
Change-Id: I06dd6436cc34a37b4966fddc888fade982ea51bd
Closes-Bug: #1492648
e569d80182