refactor to put fav_id on FaUserPostFav

rake/fa.rake

@@ -131,7 +131,7 @@ namespace :fa do
     ).perform_later({ url_name: url_name, force_scan: true })
   end
 
-  desc "backfill FaFavIdAndDate from exisitng user page and favs scans"
+  desc "backfill FaUserPostFav from exisitng user page and favs scans"
   task backfill_favs_and_dates: %i[set_logger_stdout environment] do
     start_at = ENV["start_at"]
     mode = ENV["mode"] || "both"