CiBuildsCollector::PER_RUNNER_QUERY assumes mirror features not available in CE
Description
For my CE install, I noticed the following error logged periodically in association with GitLab Monitor's DB checks:
==> /var/log/gitlab/postgresql/current <==
2017-05-19_05:22:54.35893 ERROR: column projects.mirror does not exist at character 57
2017-05-19_05:22:54.35902 STATEMENT: SELECT ci_builds.runner_id, ci_runners.is_shared, projects.mirror, projects.pending_delete, projects.mirror_trigger_builds, COUNT(*) AS count FROM ci_builds JOIN ci_runners ON ci_runners.id = ci_builds.runner_id JOIN projects ON projects.id = ci_builds.project_id WHERE ci_builds.type = 'Ci::Build' AND ci_builds.status = 'running' GROUP BY ci_builds.runner_id, projects.mirror, projects.pending_delete, projects.mirror_trigger_builds, ci_runners.is_shared