Remove convert_target from NN tests. (#45291)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45291
It's not necessary, you can just check if the dtype is integral.
Test Plan: Imported from OSS
Reviewed By: albanD
Differential Revision: D23911963
Pulled By: gchanan
fbshipit-source-id: 230139e1651eb76226f4095e31068dded30e03e8
