Revert "[export] Copy gm before calling PassManager" for test or buil…

…d failures (pytorch#108441)

Test Plan: CI

Differential Revision: D48916322

Pull Request resolved: pytorch#108441
Approved by: https://github.com/cccclai

torch/export/__init__.py

@@ -399,7 +399,7 @@ def _transform(self, *passes: PassType) -> "ExportedProgram":
         )
 
         pm = PassManager(list(passes))
-        res = pm(copy.deepcopy(self.graph_module))
+        res = pm(self.graph_module)
         transformed_gm = res.graph_module if res is not None else self.graph_module
         assert transformed_gm is not None