Runtime config contains multi_kv_config field, which can set current store to use when ring is configured with multi KV store.

However runtime config changes are currently only reflected in ingester ring (in ingesters and distributor/querier/rulers). Reason is that only initIngesterService and initRing methods in modules.go initialize ConfigProvider in kv.MultiConfig struct.

We need to do the same in all ring configs that can use multi KV. I think we should reuse the same multi_kv_config field in runtime config for ALL ring stores.