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_prometheus.go

@@ -18,7 +18,6 @@ import (
 	"github.com/grafana/grafana/pkg/services/ngalert/eval"
 	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
 	"github.com/grafana/grafana/pkg/services/ngalert/state"
-	"github.com/grafana/grafana/pkg/services/ngalert/store"
 
 	apiv1 "github.com/prometheus/client_golang/api/prometheus/v1"
 )
@@ -26,7 +25,7 @@ import (
 type PrometheusSrv struct {
 	log     log.Logger
 	manager state.AlertInstanceManager
-	store   store.RuleStore
+	store   RuleStore
 	ac      accesscontrol.AccessControl
 }