Usagestats: Add stat group for alert rule groups (#78825)

* Add rule group support to usagestats service

* Quote column name

pkg/services/stats/models.go

@@ -26,6 +26,7 @@ type SystemStats struct {
 	DashboardVersions         int64
 	Annotations               int64
 	AlertRules                int64
+	RuleGroups                int64
 	LibraryPanels             int64
 	LibraryVariables          int64
 	DashboardsViewersCanEdit  int64

pkg/services/stats/statsimpl/stats.go

@@ -128,6 +128,9 @@ func (ss *sqlStatsService) GetSystemStats(ctx context.Context, query *stats.GetS
 		sb.Write(`(SELECT COUNT(*) FROM ` + dialect.Quote("data_keys") + `WHERE active = true) AS active_data_keys,`)
 		sb.Write(`(SELECT COUNT(*) FROM ` + dialect.Quote("dashboard_public") + `) AS public_dashboards,`)
 		sb.Write(`(SELECT MIN(timestamp) FROM ` + dialect.Quote("migration_log") + `) AS database_created_time,`)
+		if ss.IsUnifiedAlertingEnabled() {
+			sb.Write(`(SELECT COUNT(DISTINCT (` + dialect.Quote("rule_group") + `)) FROM ` + dialect.Quote("alert_rule") + `) AS rule_groups,`)
+		}
 
 		sb.Write(ss.roleCounterSQL(ctx))