[FX] Only copy over training attr if it\'s there (#44314)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44314
Test Plan: Imported from OSS
Reviewed By: dzhulgakov
Differential Revision: D23578189
Pulled By: jamesr66a
fbshipit-source-id: fb7643f28582bd5009a826663a937fbe188c50bc
