Alerting: Add state_periodic_save_batch_size config option (#98019)

* Alerting: Add state_periodic_save_batch_size config option

---------

Co-authored-by: brendamuir <100768211+brendamuir@users.noreply.github.com>

pkg/setting/setting_unified_alerting.go

@@ -114,9 +114,10 @@ type UnifiedAlertingSettings struct {
 	RecordingRules                RecordingRuleSettings
 
 	// MaxStateSaveConcurrency controls the number of goroutines (per rule) that can save alert state in parallel.
-	MaxStateSaveConcurrency   int
-	StatePeriodicSaveInterval time.Duration
-	RulesPerRuleGroupLimit    int64
+	MaxStateSaveConcurrency    int
+	StatePeriodicSaveInterval  time.Duration
+	StatePeriodicSaveBatchSize int
+	RulesPerRuleGroupLimit     int64
 
 	// Retention period for Alertmanager notification log entries.
 	NotificationLogRetention time.Duration
@@ -457,6 +458,8 @@ func (cfg *Cfg) ReadUnifiedAlertingSettings(iniFile *ini.File) error {
 		return err
 	}
 
+	uaCfg.StatePeriodicSaveBatchSize = ua.Key("state_periodic_save_batch_size").MustInt(1)
+
 	uaCfg.NotificationLogRetention, err = gtime.ParseDuration(valueAsString(ua, "notification_log_retention", (5 * 24 * time.Hour).String()))
 	if err != nil {
 		return err