WinRM timeout

_This issue was originally opened by @jmmeacham as hashicorp/packer#10808. It was migrated here as a result of the [Packer plugin split](https://github.com/hashicorp/packer/issues/8610#issuecomment-770034737). The original body of the issue is below._

Ah, that explains it! Then there's some validation we can add, good find!

_Originally posted by @carlpett in https://github.com/hashicorp/packer/issues/8661#issuecomment-591283966_

I'm still having the issue as well. The machine is built, but then aborts, so I know it's authenticating.

No file, test, or entry point is named in the migrated issue. Start by reproducing the WinRM timeout during a Proxmox builder run and tracing the plugin's authentication and validation path. The issue does not define the expected validation or a precise done condition, so that scope needs clarification first.

Written by the indexing model from the issue text.