WIP: Enable excluding specific components from service rate aggregations

Adds a label (non_service_rate) that if true, will exclude a specific gitlab_component_ops:rate* metric from being included in the gitlab_service_ops:rate* metrics, and uses this to exclude secondary redis servers from polluting the core service rate

This is preferable to !2316 (closed) as it keeps the service rate aggregation rules fairly agnostic and means we're indicating intent from the lower levels up to the higher, rather than having to know about redis (or others) specifically.

NB: the actual name of the label is utterly negotiable. The only alternative I could come up with was exclude_from_service_rate which feels a bit long, but is more descriptive. I'm very open to alternatives.