Generating services' recording rules per supported tenant(s)

Part of gitlab-com/gl-infra/scalability#2768 (closed).

Every week someone gets annoyed by the fact that we are generating too many recording rules targeting tenants not relevant to a service, so I went ahead and implemented this.

This does not implement the tenant target for saturation points, only per service. It's a starting point and maybe the most relevant to get rid of some useless duplications.