Torchelastic: make process failure init error non-fatal (#56739)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56739
The diff makes several tiny changes:
* Add logs for each worker error file destination
* Make sure log_dir is propagated from the launcher
* Make ProcessFailure initialization error non-fatal.
Test Plan:
buck test mode/dev-nosan //caffe2/test/distributed/elastic/multiprocessing/errors:api_test
https://fburl.com/tupperware/0nizb9z8
Reviewed By: borovsky-d, wilson100hong
Differential Revision: D27952596
fbshipit-source-id: 69582bf4be47758def4008f2abf82d123294cd1a
