Chore: Clean up old navigation (#66287)

* remove code outside of the topnav feature flag

* delete NavBar folder

* remove topnav toggle from backend

* restructure AppChrome folder

* fix utils mock

* fix applinks tests

* remove tests since they're covered in e2e

* fix 1 of the approotpage tests

* Fix another dashboardpage test

* remove reverse portalling + test for plugins using deprecated onNavChanged method

* kick drone

* handle correlations

public/app/features/folders/components/NewDashboardsFolder.tsx

@@ -54,7 +54,6 @@ function NewDashboardsFolder({ createNewFolder }: Props) {
   return (
     <Page navId="dashboards/browse" pageNav={pageNav}>
       <Page.Contents>
-        {!config.featureToggles.topnav && <h3>New dashboard folder</h3>}
         <Form defaultValues={initialFormModel} onSubmit={onSubmit}>
           {({ register, errors }) => (
             <>