Run the test suite in KVM runners

cc @bentiss, @FFY00

The previous test suite merely ran flake8 and the pip3 install process to verify basic sanity. The actual test suite wasn't run because we needed VMs to create devices.

This MR adds the gitlab-ci.yml snippets to create a container with ci-templates and use that container. No image deletion snippet is currently present, ci-templates doesn't help with that yet. Some minor fixes required for the tests.

Obsoletes !12 (closed)

Note to self: it's amazing how often one can typo the word .success...