Allow runas env retrieval to not block.

[scott-sturdivant]

What does this PR do?

Add a timeout to subprocess call to retrieve runas user's environment.

IMO, this PR is incomplete for at least two reasons:

• Timeout is hardcoded as 10. Does salt have a preferred way to make this configurable?
• No tests. May need help mocking out the subprocess call.

What issues does this PR fix or reference?

Fixes: 63901

Previous Behavior

On certain systems, the subprocess call to retrieve the runas user's environment would hang indefinitely. By applying a timeout, this process can at least continue.

New Behavior

Timeout allows the execution flow to continue.

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

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[scott-sturdivant]

Been running this patch in our environment on 3005, 3006, and now 3006.1 with success.