FsDataSetImpl#checkAndUpdate should delete duplicated block meta file.

Think about below case :

We have one datanode called dn1,   it has two storages call ds1 and ds2 respectively.

Suppose we have blk_123 and blk_123_1001.meta in ds1 and blk_123_1001.meta in ds2.

The current logic will not handle the file blk_123_1001.meta in ds2 and only prints logs to tell us DirectoryScanner scan missing block files.

I think we should do something here.