fix incorrect default on Graph::toString (#21370)
Summary:
This default was incorrect and made printing in python not print file:line:col
This wasn't caught because FileCheck internally uses operator<< to print the graph, which has `true` hardcoded as the value. I've added more comprehensive tests to catch this
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21370
Differential Revision: D15631135
Pulled By: jamesr66a
fbshipit-source-id: c809e06fff4f0174eefeb89062024384b4944ef7
