Upgrade gitlabrunner

Adding support for gitlab runner upgrading.

Task will allow bigbang-ci to upgrade helper-image and job image (gitlab-runner-helper and ubi8) in all (privileged|generic)-runner-hr.yaml files located under bb_prod/apps/gitlab-runners space.

Script will use the new version of bigbang (submitted by renovate via postupgradetask) to pull and identify the actual, vetted version of gitlab runner for that specific release. This will allow it to work even if the new bigbang had to explicitly use a previous version of these runners without moving HEAD back on those subprojects, or if the renovate task simply runs too long after the release has been cut and a new tag of the runner has been released.

This process may become considerably simpler once subcharts are converted to OCI form, as all charts/versions will become dependencies of the bigbang chart/Chart.yaml, though at that point we may need to extend renovate-runner to use additional helm commands (or another tool) to read OCI charts