Alerting: Enable group-level rule evaluation jittering by default, remove feature toggle (#82212)

* remove jitter feature flag

* Add an out so users can manually disable jitter

* Pass in cfg

* Add TODO to remove knob in future

pkg/services/ngalert/ngalert.go

@@ -274,7 +274,7 @@ func (ng *AlertNG) init() error {
 		BaseInterval:         ng.Cfg.UnifiedAlerting.BaseInterval,
 		MinRuleInterval:      ng.Cfg.UnifiedAlerting.MinInterval,
 		DisableGrafanaFolder: ng.Cfg.UnifiedAlerting.ReservedLabels.IsReservedLabelDisabled(models.FolderTitleLabel),
-		JitterEvaluations:    schedule.JitterStrategyFrom(ng.FeatureToggles),
+		JitterEvaluations:    schedule.JitterStrategyFrom(ng.Cfg.UnifiedAlerting, ng.FeatureToggles),
 		AppURL:               appUrl,
 		EvaluatorFactory:     evalFactory,
 		RuleStore:            ng.store,

pkg/services/ngalert/schedule/jitter.go

@@ -7,6 +7,7 @@ import (
 	"github.com/grafana/grafana-plugin-sdk-go/data"
 	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	ngmodels "github.com/grafana/grafana/pkg/services/ngalert/models"
+	"github.com/grafana/grafana/pkg/setting"
 )
 
 // JitterStrategy represents a modifier to alert rule timing that affects how evaluations are distributed.
@@ -19,14 +20,14 @@ const (
 )
 
 // JitterStrategyFrom returns the JitterStrategy indicated by the current Grafana feature toggles.
-func JitterStrategyFrom(toggles featuremgmt.FeatureToggles) JitterStrategy {
-	strategy := JitterNever
+func JitterStrategyFrom(cfg setting.UnifiedAlertingSettings, toggles featuremgmt.FeatureToggles) JitterStrategy {
+	strategy := JitterByGroup
+	if cfg.DisableJitter {
+		return JitterNever
+	}
 	if toggles == nil {
 		return strategy
 	}
-	if toggles.IsEnabledGlobally(featuremgmt.FlagJitterAlertRules) {
-		strategy = JitterByGroup
-	}
 	if toggles.IsEnabledGlobally(featuremgmt.FlagJitterAlertRulesWithinGroups) {
 		strategy = JitterByRule
 	}