[JIT][Easy] Shape cleanups (#65148)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65148
No functional changes, factoring out optimizations and renaming the `graph` in symbolic shape analysis to `shape_compute_graph` as ZolotukhinM suggested
Test Plan: Imported from OSS
Reviewed By: navahgar
Differential Revision: D31797447
Pulled By: eellison
fbshipit-source-id: 60d322da040245dd7b47ee7c8996239572fd11c2
