using --start-at-task causes keystone resource management to fail

[Alex Schultz]

If you run the ansible deployment playbook using a --start-at-task that skips the global vars loading, the keystone resource tasks fail because keystone_resources is undefined. We should include a global var loading/check if keystone_resources is undefined.

2021-01-26 18:22:36.581518 | fa163eb6-0b6b-33ca-ae8e-0000000019db | TASK | Create Keystone Projects
2021-01-26 18:22:36.622582 | fa163eb6-0b6b-33ca-ae8e-0000000019db | FATAL | Create Keystone Projects | undercloud | error={"msg": "{{ keystone_resources }}: 'keystone_resources' is undefined"}

[Alex Schultz (alex-schultz)]

https://review.opendev.org/c/openstack/tripleo-heat-templates/+/772585

[Alex Schultz (alex-schultz)]

This can be avoided by -e @global-vars.yaml when using --start-at-tasks

[Alex Schultz (alex-schultz)]

Documented https://docs.openstack.org/project-deploy-guide/tripleo-docs/latest/deployment/ansible_config_download.html#server-specific-pre-and-post-deployments