Use non-Variable type for callsites that check type equality (#16325)

Use non-Variable type for callsites that check type equality (#16325)

Summary:
When Variable and Tensor are merged, the dynamic type of the tensors passed to certain functions will become variables, and expecting `type()` on those variables to still return non-Variable types will cause type mismatch error.

One way to fix this problem is to use the thread-local guard `at::AutoNonVariableTypeMode` to force `type()` to return non-Variable type, but ideally we want to limit the use of `at::AutoNonVariableTypeMode` to be only in VariableType.cpp. Another way to fix the problem is to use `at::globalContext().getNonVariableType()` instead to get the non-Variable type of the tensor, which is what this PR is trying to achieve.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16325

Differential Revision: D14012022

Pulled By: yf225

fbshipit-source-id: 77ef1d2a02f78bff0063bdd72596e34046f1e00d