The limit ruler.max-rule-groups-per-tenant-by-namespace looks at the rule grous in all namespace

[gotjosh]

In #8425, we introduced this limit as an override to the value defined in RulerMaxRuleGroupsPerTenant. However, I have realised that it might be causing more confusion because the expectation seems to be that this is a new value that is JUST for the particular namespace.

As worded, the limit might seem to indicate the limit of rule groups will only apply to the rule groups in the defined namespace and not globally.

Allow me to explain. Assuming tenant user-1 has a total of 25 rule groups across all namespaces and is set with a limit of RulerMaxRuleGroupsPerTenant = 50, if we set something like:

ruler_max_rule_groups_per_tenant_by_namespace: {
  newnamespace: 24,
},

This is effectively a downgrade, and we'll be unable to put rules into the new namespace despite the user having plenty of room.

I think the limit should only count rule groups in the given namespace.