fix api lantency metrics

Author: oliviassss

utils/prometheusmetrics/prometheusmetrics.go

@@ -85,6 +85,10 @@ var (
 		prometheus.SummaryOpts{
 			Name: "awscni_aws_api_latency_ms",
 			Help: "AWS API call latency in ms",
+			Objectives: map[float64]float64{
+				0.5:  0.05,  // p50 ±5%
+				0.99: 0.001, // p99 ±0.1%
+			},
 		},
 		[]string{"api", "error", "status"},
 	)