poe based gitlab runner pipeline

This MR directly supports work to run cypress tests in a front end repo: https://gitlab.developers.cam.ac.uk/uis/devops/iam/activate-account/frontend/-/issues/?sort=created_date&state=opened&first_page_size=20&show=eyJpaWQiOiIyNiIsImZ1bGxfcGF0aCI6InVpcy9kZXZvcHMvaWFtL2FjdGl2YXRlLWFjY291bnQvZnJvbnRlbmQiLCJpZCI6OTk5NzZ9

From a generic perspective, it's part of a POC new way to run tests in our pipelines, with more detail avialable here: https://guidebook.devops.uis.cam.ac.uk/howtos/git-gitlab/poe-test-pipeline/