Inform Arel we don't need additional type casting in batches

Part of the larger refactoring to remove type casting from Arel. We can
inform it that we already have the right type by wrapping the value in
an `Arel::Nodes::Quoted`. This commit can be reverted when we have
removed type casting from Arel in Rail 5.1

activerecord/lib/active_record/relation/batches.rb

@@ -52,7 +52,12 @@ module ActiveRecord
         end
       else
         enum_for :find_each, options do
-          options[:start] ? where(table[primary_key].gteq(options[:start])).size : size
+          # FIXME: Remove this when type casting is removed from Arel
+          # (Rails 5.1). We can pass start directly instead.
+          if options[:start]
+            quoted_start = Arel::Nodes::Quoted.new(options[:start])
+          end
+          options[:start] ? where(table[primary_key].gteq(quoted_start)).size : size
         end
       end
     end