Ensure that lifted tensor constants don't show up as inputs in emitted program (#1897)

Summary:
Currently lifted tensor constants are showing up as inputs to the emitted program. This shouldn't be the case as they're embedded inside the program as constants and the user will not be passing these in as inputs.

Pull Request resolved: https://github.com/pytorch/executorch/pull/1897

Reviewed By: chakriu, angelayi

Differential Revision: D53584903

Pulled By: tarun292

fbshipit-source-id: 9349bc20216f9ffe877fc6e32df17409f1131e83