The official podman ubuntu install guide[1] tells to install podman from
Kubic project repo for ubuntu Bionic and Focal. And project atomic PPA
repo[2] is deprecated.
But Kubic repo only provides x86_64 deb packages for Bionic. For non x86_64
platforms use project atomic PPA repo on Bionic.
Also add a job zuul-jobs-test-ensure-podman-ubuntu-focal.
[1] https://podman.io/getting-started/installation
[2] https://launchpad.net/~projectatomic/+archive/ubuntu/ppa
Change-Id: I402adf1866e4bb8f3b388216bc48b9927e1388b1
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