Fix another hang on shutdown (#51681)

Fix another hang on shutdown (#51681)

* Fix another hang on shutdown
- If SIGINT/Ctrl+C fires don't block shutdown waiting for dispose. This mechanism was intended to be a way to let application code unwind completely before exiting the process but we can cancel the the CancelKeyPress today, which means we don't need to wait for dispose to be called.
- This is a change in behavior but I can't figure out a case where ProcessExit would fire and you'd want it to wait on a dispose call *after* SIGINT/CTRL+C has fired.