fetch bucket replication stats across peers in single call (#14956)

current implementation relied on recursively calling one bucket
at a time across all peers, this would be very slow and chatty
when there are 100's of buckets which would mean 100*peerCount
amount of network operations.

This PR attempts to reduce this entire call into `peerCount`
amount of network calls only. This functionality addresses also a
concern where the Prometheus metrics would significantly slow
down when one of the peers is offline.

cmd/metrics-v2.go

@@ -1604,8 +1604,9 @@ func getBucketUsageMetrics() *MetricsGroup {
 			Value:       float64(time.Since(dataUsageInfo.LastUpdate)),
 		})
 
+		bucketReplStats := getAllLatestReplicationStats(dataUsageInfo.BucketsUsage)
 		for bucket, usage := range dataUsageInfo.BucketsUsage {
-			stats := getLatestReplicationStats(bucket, usage)
+			stats := bucketReplStats[bucket]
 
 			quota, _ := globalBucketQuotaSys.Get(ctx, bucket)