feat: show organization username in impersonation banner (#24313)

- Update ImpersonatingBanner to use orgAwareUsername field from session
- Falls back to regular username for non-organization users
- Uses existing session data without additional queries

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: Anik Dhabal Babu <81948346+anikdhabal@users.noreply.github.com>

packages/features/ee/impersonation/components/ImpersonatingBanner.tsx

@@ -17,7 +17,7 @@ function ImpersonatingBanner({ data }: ImpersonatingBannerProps) {
   return (
     <>
       <TopBanner
-        text={t("impersonating_user_warning", { user: data.user.username })}
+        text={t("impersonating_user_warning", { user: data.user.orgAwareUsername || data.user.username })}
         variant="warning"
         actions={
           canReturnToSelf ? (