Adds timeout argument to training_args to avoid socket timeouts in DDP
Author: gugarosa
Pull request: yes

# What does this PR do?

This PR follows the work done in #18081 and adds a `timeout` argument to `TrainingArgs` to avoid Socket Timeouts when using PyTorch's `torch.distributed.init_process_group`: https://pytorch.org/docs/stable/distributed.html#torch.distributed.init_process_group

_`timeout` argument exists since 1.0.0: https://pytorch.org/docs/1.0.0/distributed.html. This prevents any regression._

Fixes #18054 #17106 and finishes the open PR #18081.

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Comments:
_The documentation is not available anymore as the PR was closed or merged._

Hey @gugarosa, thanks for your PR! I'm asking Sylvain to review it as he's the maintainer of the `Trainer`, but he's on the leave for the next few weeks. He'll review your PR when he's back!

Thanks for your patience :pray: 

No worries @LysandreJik! Thanks so much for the attention!

You just need to run `make style` and we should be good!

> You just need to run `make style` and we should be good!

My bad! I always forget to run it. Just squashed the previous commits and added the `make style`. Hopefully, it will pass all tests in a couple minutes!

Thanks for all the attention on this PR!