In the near future, Github will use Ubuntu 20.04, for workflows, and
this change will keep the upstream CI environment consistent between
Github and Azure.
Added comment about problem with no_log in Azure CI. While running on CI
using ansible 2.10a the content of attributes with no_log=True is
replaced by ***** on ansible causing test failures.
* Moved azure CI definitions from azure-pipelines.yml to
tests/azure/azure-pipelines.yml.
* Updated azure CI definitions to run playbook tests using docker
containers.