Fix the editlog corruption exposed by failed TestAddStripedBlocks

TestAddStripedBlocks failed with some editlog corruption. Did some debugging, I can see at least two issues:

1. DFSStripedOutputStream tries to send out an empty packet to close the block even if writing 0 bytes
2. Because of the above, NN tries to close the file. This exposes another bug in BlockInfoStriped, which writes its data/parity block numbers into the close editlog but do not read them while loading.

This jira aims to only fix #2 and HDFS-8166 is used for fixing #1.