This defines which release we upgrade from in CI.

Also remove some Wallaby upgrade compatibility code in CI playbooks

Change-Id: I18912178392973337ca4115dec3816f1b3944ad5

By default, Ansible injects a variable for every fact, prefixed with
ansible_. This can result in a large number of variables for each host,
which at scale can incur a performance penalty. Ansible provides a
configuration option [0] that can be set to False to prevent this
injection of facts. In this case, facts should be referenced via
ansible_facts.<fact>.

This change updates all references to Ansible facts within Kolla Ansible
from using individual fact variables to using the items in the
ansible_facts dictionary. This allows users to disable fact variable
injection in their Ansible configuration, which may provide some
performance improvement.

This change disables fact variable injection in the ansible
configuration used in CI, to catch any attempts to use the injected
variables.

[0] https://docs.ansible.com/ansible/latest/reference_appendices/config.html#inject-facts-as-vars

Change-Id: I7e9d5c9b8b9164d4aee3abb4e37c8f28d98ff5d1
Partially-Implements: blueprint performance-improvements

Change-Id: I77791d504327ace880d0cc2438af2f8ced66d4eb

This should improve performance of CI jobs.

Change-Id: I729862b89b4fe65cbb7f852fac06741b636e4939

Continue to reduce the scope of setup_gate.sh. Allows us to more easily
select python 2 or 3.

Change-Id: If2eeeacbbbdf58afb765b4a39772b5a1af7b952b
Partially Implements: blueprint python-3