Replace the stack.yaml workbook with a non-Mistral solution and deprecate workflows

[Dougal Matthews]

Without the tripleo-ui, there is little advantage to Mistral in tripleo. We can simplify the architecture by deprecating and removing it.

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/687524

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/687531

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.opendev.org/687533

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/687524
Committed: https://git.openstack.org/cgit/openstack/tripleo-ansible/commit/?id=8bae3481ede4ab2d10fd31ec03af096ea13e7361
Submitter: Zuul
Branch: master

commit 8bae3481ede4ab2d10fd31ec03af096ea13e7361
Author: Dougal Matthews <email address hidden>
Date: Wed Oct 9 09:59:12 2019 +0100

    Add a playbook for the "openstack overcloud delete" CLI Command

    This playbook encapsulated the logic that Mistral provides for the
    overcloud delete CLI command. Replacing the following two workflows

    - tripleo.plan_management.v1.delete_deployment_plan
    - tripleo.deployment.v1.undeploy_plan

    Related-Bug: #1835242
    Related-Bug: #1835246
    Related-Bug: #1835232

    Co-Authored-By: Kevin Carter <email address hidden>
    Co-Authored-By: Luke Short <email address hidden>
    Change-Id: I38d9535d9b71fca93eb34d2018355c0f8c8fa8fd