Fix shared top locks client (#19018)

`client` is shared across goroutines.

Seen with `mc support top locks` on minio built with `-race`.

cmd/notification.go

@@ -460,6 +460,7 @@ func (sys *NotificationSys) GetLocks(ctx context.Context, r *http.Request) []*Pe
 	g := errgroup.WithNErrs(len(sys.peerClients))
 	for index, client := range sys.peerClients {
 		index := index
+		client := client
 		g.Go(func() error {
 			if client == nil {
 				return errPeerNotReachable