Resolve unused variables in tests (#24075)
Summary:
Variables such as `device` and `sparse` in for loops should be used in tests.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24075
Differential Revision: D16763073
Pulled By: ezyang
fbshipit-source-id: 8735cbc8d9ed695db8489cfc949c895180a7b826
