searchable: replace find_ordered with in_order_of.

Rails 7 added an `in_order_of` method that does what our `find_ordered`
method did before.

app/logical/concerns/searchable.rb

@@ -592,7 +592,7 @@ module Searchable
     if params[:order] == "custom"
       parse_ids = PostQueryBuilder.new(nil).parse_range(params[:id], :integer)
       if parse_ids[0] == :in
-        return find_ordered(parse_ids[1])
+        return in_order_of(:id, parse_ids[1])
       end
     end
 
@@ -603,14 +603,6 @@ module Searchable
     order(id: :desc)
   end
 
-  def find_ordered(ids)
-    order_clause = []
-    ids.each do |id|
-      order_clause << sanitize_sql_array(["#{qualified_column_for(:id)} = ? DESC", id])
-    end
-    where(id: ids).order(Arel.sql(order_clause.join(', ')))
-  end
-
   private
 
   def qualified_column_for(attr)