volume: deletion can skip volume size checking

fix https://github.com/chrislusf/seaweedfs/issues/2225

weed/storage/needle/needle_read_write.go

@@ -147,7 +147,7 @@ func (n *Needle) Append(w backend.BackendStorageFile, version Version) (offset u
 		err = fmt.Errorf("Cannot Read Current Volume Position: %v", e)
 		return
 	}
-	if offset >= MaxPossibleVolumeSize {
+	if offset >= MaxPossibleVolumeSize && n.Size.IsValid() {
 		err = fmt.Errorf("Volume Size %d Exeededs %d", offset, MaxPossibleVolumeSize)
 		return
 	}