Enable timeout for DDPStrategy

[lsy643]

What does this PR do?

Enable timeout for DDPStrategy

Fixes #13211

Does your PR introduce any breaking changes? If yes, please list them.

None

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[justusschock]

@carmocca should we also set the env variables for the non-gloo backends? Or at least check them and error out early?

[carmocca]

LGTM as it is!

Let's continue the discussion about the env vars in the issue and if necessary, open a separate PR for checking them.

[RuABraun]

How is one supposed to use this in a yaml config? the timeout arg is class with a named arg.