Disable free CI/CD for GitHub for private projects without a paid subscription on March 22
When launching support for GitHub projects using GitLab CI, we made CI/CD for GitHub on GitLab.com available for everyone for 1 year. This was extended a few times (most recently https://about.gitlab.com/blog/2019/09/09/ci-cd-github-extended-again/). Now that the free period is ending - see https://gitlab.com/gitlab-com/Product/issues/785 for discussion (internal only), we need to revert this change.
Note that this needs to be effective on March 22, not before.