[goal] Migrate patrole jobs to focal

As per victoria cycle testing runtime and community goal[1]
we need to migrate upstream CI/CD to Ubuntu Focal(20.04).

Most of the Tempest jobs will be migrate automatically once devstack
base job start running on Focal(Depends-On).

stable jobs testing stable branch needs to keep running on their supported
distro version which is bionic from stein till ussuri.

Also fixing few lower constraints.

[1] https://governance.openstack.org/tc/goals/selected/victoria/migrate-ci-cd-jobs-to-ubuntu-focal.html

Change-Id: Id1799fee94071c2eaea17bc50ef2845a8489fa92
2 files changed