Use DefaultLogins instead of Default display names when calling
MultiSelectWithSearch for reviewers. The dedup logic in the
prompter compares keys (logins) against defaults, so passing
display names like 'mxie (Melissa Xie)' prevented deduplication
against search result keys like 'mxie'.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>