Nexus updates

Update .gitlab-ci.yml to use image: docker-registry.default.svc:5000/openshift/gitlab-runner@sha256:0dc9bdda813b1d7a9978960866eeaf736ecd1d4b60bbff5c2d0995c88d77021c and update DCAR_REGISTRY CI/CD variable to nexus-docker-levelup-nexus.apps.cluster.levelup-staging.io. Test role to make sure its successful and the application is available.