Restructure train/: nest shards into chunk subdirs (batch 97/98)

Restructure train/: nest shards into chunk subdirs (batch 81/98)

Restructure train/: nest shards into chunk subdirs (batch 80/98)

Restructure train/: nest shards into chunk subdirs (batch 79/98)

Restructure train/: nest shards into chunk subdirs (batch 78/98)

Restructure train/: nest shards into chunk subdirs (batch 77/98)

Restructure train/: nest shards into chunk subdirs (batch 76/98)