Avoid wrong way to delete on replication failure

Avoid wrong way to delete on replication failure. This deletion has bug
to write. The better fix is not to use the deletion on failure at all.

go/weed/weed_server/volume_server_handlers_write.go

@@ -67,7 +67,6 @@ func (vs *VolumeServer) DeleteHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	n.Size = 0
 	ret := topology.ReplicatedDelete(vs.GetMasterNode(), vs.store, volumeId, n, r)
 
 	if ret != 0 {