DEV: Remove code that is no longer used (#17684)

app/assets/javascripts/discourse/app/routes/application.js

@@ -51,10 +51,6 @@ const ApplicationRoute = DiscourseRoute.extend(OpenComposer, {
       mobile.toggleMobileView();
     },
 
-    toggleSidebar() {
-      this.controllerFor("application").send("toggleSidebar");
-    },
-
     logout: unlessReadOnly(
       "_handleLogout",
       I18n.t("read_only_mode.logout_disabled")

app/assets/javascripts/discourse/app/templates/components/sidebar.hbs

@@ -1,6 +1,6 @@
 <DSection @pageClass="has-sidebar" @class="sidebar-container" @scrollTop={{false}}>
   <div class="sidebar-scroll-wrap">
     <Sidebar::Sections @collapsableSections={{true}}/>
-    <Sidebar::Footer @toggleSidebar={{@toggleSidebar}} @tagName=""/>
+    <Sidebar::Footer @tagName=""/>
   </div>
 </DSection>

app/assets/javascripts/discourse/app/templates/components/sidebar/hamburger-dropdown.hbs

@@ -4,7 +4,7 @@
       <div class="panel-body-content">
         <div class="sidebar-hamburger-dropdown">
           <Sidebar::Sections @collapsableSections={{false}}/>
-          <Sidebar::Footer @toggleSidebar={{route-action "toggleSidebar"}} @tagName="" />
+          <Sidebar::Footer @tagName="" />
         </div>
       </div>
     </div>