[PyTorch Mobile]Fix unit test (#58202)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58202
This unit test was testing the wrong target. It should test the sampler under jit::mobile. This diff fixes it.
Test Plan: run unit tests
Reviewed By: shreyanb98
Differential Revision: D28384839
fbshipit-source-id: 35cc63be2e73ca9b1a7d30d6f67fffcfe5021fa2
