fix some tests that I accidentally disabled (#15077)
Summary:
While moving these scenarios into `_test_dim_ops` I accidentally left an empty loop in the actual tests, causing them to do nothing.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15077
Differential Revision: D13428759
Pulled By: umanwizard
fbshipit-source-id: 08f53068981d9192c1408878b168e9053f4dc92e
