Add support for deploying with docker to devstack

[vyzigold]

In upstream openstack CI on older stable branches (for example stable/yoga), we use ubuntu based VMs, which don't yet have the podman package it their package manager and the installation fails. For these distros, we need to use docker instead.

I added a code, that would install docker if it fails to install podman. It also configures docker to be usable by the stack user.

I should note, that I wasn't able to create a ubuntu 20.04 or ubuntu 18.04 VM, which should be the affected ubuntus so I tested with debian 10 instead, which also doesn't have podman. I wasn't able to get the whole devstack deployed though, because debian 10 isn't supported and it failed because of unrelated issues, but the devstack got far enough to execute the install_container_executable here. It correctly installed docker and I was able to execute the rest of the steps in this plugin manually without issues.

[softwarefactory-project-zuul]

Build failed (check pipeline). Post recheck (without leading slash)
to rerun all jobs. Make sure the failure cause has been resolved before
you rerun jobs.

https://review.rdoproject.org/zuul/buildset/5907ae12606a42d5b1e852142b8717c5

❌ stf-crc-ocp_412-nightly_bundles NODE_FAILURE Node request 200-0006664841 failed in 0s
❌ stf-crc-ocp_412-local_build NODE_FAILURE Node request 200-0006664842 failed in 0s
❌ stf-crc-ocp_413-nightly_bundles NODE_FAILURE Node request 200-0006664843 failed in 0s
✔️ stf-crc-ocp_413-local_build SUCCESS in 37m 51s

[leifmadsen]

We can ignore rdoproject.org/github-check job here since it isn't covered by CI.