Alerting: Change rule migration to be based on feature flag (#33792)

makes it so the feature flag can be turned on off, and the migration will be cleared and rerun. All existing NG alert rules, configuration settings, etc are removed when disabling the feature flag.
for https://github.com/grafana/alerting-squad/issues/142

Co-authored-by: Sofia Papagiannaki <sofia@grafana.com>

pkg/services/sqlstore/sqlstore.go

@@ -85,7 +85,7 @@ func (ss *SQLStore) Init() error {
 	dialect = ss.Dialect
 
 	if !ss.dbCfg.SkipMigrations {
-		migrator := migrator.NewMigrator(ss.engine)
+		migrator := migrator.NewMigrator(ss.engine, ss.Cfg)
 		migrations.AddMigrations(migrator)
 
 		for _, descriptor := range registry.GetServices() {