[LTC] Fix stride accessors in LTCTensorImpl (#70623)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/70623
Strides on lazy tensor should only be read after calling setup_size_properties. This fixes a failure in hf_Longformer.
Test Plan: CI on the lazy_tensor_staging branch
Reviewed By: wconstab, alanwaketan
Differential Revision: D33410142
Pulled By: desertfire
fbshipit-source-id: ccb2ba8d258bdb88f6b51be6196563f9c4c06cbf
