Replace str by repr for DataChunk (#63184)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/63184
Test Plan: Imported from OSS
Reviewed By: bdhirsh
Differential Revision: D30288892
Pulled By: ejguan
fbshipit-source-id: 45c88fdd3987e234f2c22ebbbfd8d5044983c34c
