Do not hard code common parameters in module help test any more

[bergmeister]

PR Summary

To prevent the test from failing again in future if PowerShell adds common parameters. Also checked that this works in WMF4 build that I still run in my fork.

PR Checklist

• PR has a meaningful title
  • Use the present tense and imperative mood when describing your changes
• Summarized changes
• Change is not breaking
• Make sure all .cs, .ps1 and .psm1 files have the correct copyright header
• Make sure you've added a new test if existing tests do not effectively test the code changed and/or updated documentation
• This PR is ready to merge and is not Work in Progress.
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[JamesWTruher]

lgtm