[fx] Arg normalization not save output node in the node_map (#58058)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58058
Don't save output node in the `node_map` because the result of output node could be a list of proxies and would throw an error when being used as key.
Test Plan: CI
Reviewed By: mikekgfb
Differential Revision: D28329580
fbshipit-source-id: a29f3ef1763930faa20cb20eb9ffd04ef7e52dc1
