Fix WSLC parser unit test argument overrides (#41496)

Update the remaining parser test call site to use ArgumentOverrides after the Argument::Create API change.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Ben Hillis <benhill@ntdev.microsoft.com>
Copilot-Session: eb7946ff-cc0b-4ff1-a059-571334b1c988