A quick check of the Ansible fact cache on Bridge indicates that only
hosts that are no longer in our inventory were Bionic nodes. Since we no
longer have any Bionic nodes in production let's rip out the testing of
our roles, playbooks and services on Bionic.
In addition to being good for clarity this also allows us to switch all
of the system-config jobs back to using the default ansible version for
the opendev zuul tenants (11) which did not work with Bionic.
Change-Id: I4e310adee198d6eedc19e499b05638eff2805a1e
bd9a81ba68