[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: D31732421
Pulled By: eellison
fbshipit-source-id: e934507d1795e0bc4d98a3bfe6cb792e2f08b119
