[master] Fix file.is_link hangs on paths that are hung mounts

[nicholasmhughes]

What does this PR do?

See issue for details.

What issues does this PR fix or reference?

Fixes: #66096

Previous Behavior

It was possible for the file.is_link function to hang if the target was on a hung mount.

New Behavior

The nostat parameter handles link checking in a way that won't hang in those circumstances.

Merge requirements satisfied?

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

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

Commits signed with GPG?

Yes

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[Kickball]

Thanks for up-streaming this 👍

[Kickball]

LGTM - thanks for the changes!