add support for configurable replication MRF workers (#12125)

just like replication workers, allow failed replication
workers to be configurable in situations like DR failures
etc to catch up on replication sooner when DR is back
online.

Signed-off-by: Harshavardhana <harsha@minio.io>

cmd/bucket-replication-stats.go

@@ -36,9 +36,9 @@ func (b *BucketReplicationStats) hasReplicationUsage() bool {
 
 // ReplicationStats holds the global in-memory replication stats
 type ReplicationStats struct {
-	sync.RWMutex
 	Cache      map[string]*BucketReplicationStats
-	UsageCache map[string]*BucketReplicationStats // initial usage
+	UsageCache map[string]*BucketReplicationStats
+	sync.RWMutex
 }
 
 // Delete deletes in-memory replication statistics for a bucket.