Reduce size of test_unsqueeze to resolve consistent timeout issue (#45877)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45877
apex_test_L0_optimizers
Test Plan: `buck test mode/dev-tsan //caffe2/test:tensorexpr -- 'test_unsqueeze \(test_tensorexpr\.TestTensorExprFuser\)' --run-disabled`
Reviewed By: malfet
Differential Revision: D24126211
fbshipit-source-id: e38ba0168b6dd44459c070c01e3e39c93d5fae42
