fix: api handlers. add tests

internal/lg/metric.go

@@ -48,7 +48,9 @@ func initMetrics(ctx context.Context, name string) (context.Context, func() erro
 		host = h
 	}
 
-	config := prometheus.Config{}
+	config := prometheus.Config{
+		DefaultHistogramBoundaries: []float64{1, 2, 5, 10, 20, 50},
+	}
 	cont := controller.New(
 		processor.NewFactory(
 			selector.NewWithHistogramDistribution(