Remove unneeded sidebar class

app/views/layouts/_page.html.haml

-.page-with-sidebar.js-page-with-sidebar{ class: [('page-with-new-sidebar' if @new_sidebar), page_gutter_class] }
+.page-with-sidebar.js-page-with-sidebar{ class: page_with_sidebar_class }
   - if show_new_nav?
     - if defined?(nav) && nav
       = render "layouts/nav/#{nav}"