Create project to store GitLab Snowplow events

While we currently use the self-monitoring project to store Snowplow events, we should consider moving them to a separate project, as described in this comment:

A few suggestions:

1. Call the group GitLab Instance instead of GitLab Instance Administrators since you might invite non-admins to it.
2. Have different projects for each piece different functionality (Metrics / Logs / Tracing / Product Analytics / Load testing / WAF /Container Host Security / Container Network Security / Alerts / Errors/ etc.) since you might want different people invited to each piece of functionality.
3. Existing instances click a button to do it until the next major version of GitLab when we create it automatically.

/cc @jeromezng