[torch/elastic] Revise the rendezvous exception types. (#54803)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/54803
Revise the rendezvous exception types to align their naming convention more closely with the standard Python exception types.
Test Plan: Run the existing test suite.
Reviewed By: H-Huang
Differential Revision: D27327505
fbshipit-source-id: 862c59222f9ca61a0e5afde89ae8f226090b4f92
