[FX] Make shape_prop handle targets with aggregate outputs (#56221)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56221
Test Plan: Imported from OSS
Reviewed By: Chillee
Differential Revision: D27810693
Pulled By: jamesr66a
fbshipit-source-id: 17c6ad671786b3bacb5026bd88b8f5b7b4b96a1a
