Alerting: Break up store.RuleStore interface, delete dead code (#55776)

* Refactor state manager to not depend on rule store interface

* Refactor grafana and proxied ruler APIs to not depend on store.RuleStore

* Refactor folder subscription logic to not use store.RuleStore

* Delete dead code

* Delete store.RuleStore

pkg/services/ngalert/api/api_ruler.go

@@ -36,7 +36,7 @@ type ConditionValidator interface {
 type RulerSrv struct {
 	xactManager        provisioning.TransactionManager
 	provenanceStore    provisioning.ProvisioningStore
-	store              store.RuleStore
+	store              RuleStore
 	QuotaService       quota.Service
 	scheduleService    schedule.ScheduleService
 	log                log.Logger