[export] Remove call_spec argument from ExportedProgram ctor. (#111407)
Summary: call_spec arg is not used anymore.
Test Plan: CI
Reviewed By: SherlockNoMad, tugsbayasgalan
Differential Revision: D50335365
Pull Request resolved: https://github.com/pytorch/pytorch/pull/111407
Approved by: https://github.com/izaitsevfb
