[2/n] add test ATen to wheel test (#62341)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/62380
* This PR introduces env variable IN_WHEEL_TEST to control the dependency on `build/` folder
* update `test_aten` function to call wheel install folder `{sitepackages}/torch` instead of `build/` folder
Pull Request resolved: https://github.com/pytorch/pytorch/pull/62341
Test Plan: check if all ci workflows pass
Reviewed By: walterddr
Differential Revision: D30004259
Pulled By: tktrungna
fbshipit-source-id: ccebd513a3530f1e5c8c9177d5f2daf14de3e853
