The `rule_groups_rules` metric is currently defined and computed by `State`.
It makes more sense for this metric to be computed off of the configured rule
set, not based on the rule evaluation state. There could be an edge condition
where a rule does not have a state yet, and so is uncounted.
Additionally, we would like this metric (and others), to have a `rule_group`
label, and this is much easier to achieve if the metric is produced from the
`Scheduler` package.
