Setup fake tensor and symbolic shapes once at beginning of AOTAutograd (#85233)
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Differential Revision: [D39662822](https://our.internmc.facebook.com/intern/diff/D39662822)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/85233
Approved by: https://github.com/wconstab
