enhance: Refine default histogram metric bucket (#34627)

/kind improvement

pr: #34580

Signed-off-by: Edward Zeng <jie.zeng@zilliz.com>

pkg/metrics/metrics.go

@@ -98,8 +98,8 @@ const (
 
 var (
 	// buckets involves durations in milliseconds,
-	// [1 2 4 8 16 32 64 128 256 512 1024 2048 4096 8192 16384 32768 65536 1.31072e+05]
-	buckets = prometheus.ExponentialBuckets(1, 2, 18)
+	// [5, 10, 20, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 3000, 10000, 60000]
+	buckets = []float64{5, 10, 20, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 3000, 10000, 60000}
 
 	// longTaskBuckets provides long task duration in milliseconds
 	longTaskBuckets = []float64{1, 100, 500, 1000, 5000, 10000, 20000, 50000, 100000, 250000, 500000, 1000000, 3600000, 5000000, 10000000} // unit milliseconds