ansible download_images slow to error out, and not multithreaded

[John Kung]

Brief Description
-----------------
Ansible Replay with Invalid Docker Registries takes 4 hours to time out.

Severity
--------

Minor: System/Feature is usable, though inefficient startup performance

Steps to Reproduce
------------------
Change your localhost.yml file to contain "invalid.docker.registry" for the location of your docker registries.

time ansible-playbook -v /usr/share/ansible/stx-ansible/playbooks/bootstrap.yml

Expected Behavior
------------------
We are prompted by error telling us that we have "invalid_docker_registries", and the playbook should fail
early (within minutes) without unnecessary delays.

Actual Behavior
----------------
Takes several hours to timeout; observed more than 4 hours.

Reproducibility
---------------
Reproducible

System Configuration
--------------------
One node system; though as this is on initial bootsrap/restore, this applied to multi-node system as well.

Branch/Pull Time/Commit
-----------------------
2021-06-09_18-58-11

Last Pass
---------
No

Timestamp/Logs
--------------
2021-05-29-06-56

Test Activity
-------------
System Test, automated regression.

Workaround
----------
Wait for timeout.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/ansible-playbooks/+/798389
Committed: https://opendev.org/starlingx/ansible-playbooks/commit/c0bc0d61a48747adc1df3a7667c206550f0b31c9
Submitter: "Zuul (22348)"
Branch: master

commit c0bc0d61a48747adc1df3a7667c206550f0b31c9
Author: John Kung <email address hidden>
Date: Mon Jun 28 17:06:47 2021 -0500

    Fix ansible download_images handle invalid registry

    Exit download_images on exception or when number of failed downloads
    threshold is exceeded. The case for invalid registries or other error,
    such as invalid DNS, is measured about 20 minutes vs 4 hours in the bug
    reported initial error case.

    The playbook will retry and pull the remaining required images; as
    docker will not pull images for the already downloaded images.

    Tests Performed:
    o initial installation and sanity which performs download_images
    o modify registries to point to invalid.docker.registry and
      measure timeouts
    o perform ansible-playbook replay with invalid registries
      Either APIError with Forbidden or 'no auth host' may occur
     (replay with invalid registry or invalid DNS)
    o perform ansible-playbook replay with good registries

    Closes-Bug: 1933863
    Signed-off-by: John Kung <email address hidden>
    Change-Id: Id2dec495ae6f956af7c66f0bcf88931991ece0c4