[FX] Fix GraphModule copy methods not regenerating forward (#44806)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44806
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D23738732
Pulled By: jamesr66a
fbshipit-source-id: 14e13551c6568c562f3f789b6274b6c86afefd0b
