[DeviceMesh][Test] Remove test_raises_mesh_dim_less_than_2 (#119172)
The test is no longer applicable after we allow 1D slice from 1D mesh. https://github.com/pytorch/pytorch/pull/118895
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119172
Approved by: https://github.com/awgu, https://github.com/atalman
