[No QA] Docs updates for E/A#89472 Suppress duplicate banner on settled paid reports

[MelvinBot]

Summary

• Updates help site docs to reflect that duplicate warnings (the Potential duplicate banner) are no longer displayed on settled/paid reports
• Adds clarification to How-to-Find-and-Resolve-Flagged-Duplicate-Expenses.md (both body and FAQ)
• Adds a note to the FAQ in Why-Expenses-Duplicate.md

Related PR: #89472

@Krishna2323, please review the files changed and confirm they reflect the current behavior. Then mark this PR Ready for review.

[OSBotify]

A preview of your ExpensifyHelp changes have been deployed to https://53b2f44d.helpdot.pages.dev ⚡️

Updated articles:

• articles/new-expensify/reports-and-expenses/How-to-Find-and-Resolve-Flagged-Duplicate-Expenses
• articles/new-expensify/reports-and-expenses/Why-Expenses-Duplicate