chore: replace sqlstore.Store with db.DB (#57010)

* chore: replace sqlstore.SQLStore with db.DB

* more post-sqlstore.SQLStore cleanup

pkg/services/comments/sql_storage.go

@@ -6,10 +6,11 @@ import (
 
 	"github.com/grafana/grafana/pkg/services/comments/commentmodel"
 	"github.com/grafana/grafana/pkg/services/sqlstore"
+	"github.com/grafana/grafana/pkg/services/sqlstore/db"
 )
 
 type sqlStorage struct {
-	sql *sqlstore.SQLStore
+	sql db.DB
 }
 
 func checkObjectType(contentType string) bool {