Rename GitLab Monitor to gitlab_exporter
## Summary The GitLab Monitor features can easily be confused with the broad-based application monitoring set of features within GitLab. The capabilities we call `GitLab Monitor` are better described as the `gitlab_exporter`. ## Improvements It eliminates the confusion between the Monitor Group within GitLab responsible for the set of application monitoring tools available within the monitor stage and the capabilities for administrators to monitor their GitLab instance. ## Risks This could potentially cause confusion from users who have used GitLab Monitor features and are now seeing it referred to as Self-Monitor. This risk is mitigated by the fact that not many users have been using self-monitor capabilities and we can provide some explanation in the release notes. ## Involved components * https://docs.gitlab.com/ee/administration/monitoring/prometheus/gitlab_monitor_exporter.html * https://gitlab.com/gitlab-org/gitlab-monitor
issue