Show service desk nav when not activated, but enabled.

app/views/layouts/nav/sidebar/_project.html.haml

@@ -138,7 +138,7 @@
                 %span
                   Milestones
 
-            - if @project.service_desk_enabled?
+            - if EE::Gitlab::ServiceDesk.enabled?(project: @project)
               = nav_link(controller: [ :issues, :service_desk ]) do
                 = link_to service_desk_project_issues_url(@project), title: 'Service Desk' do
                   %span Service Desk

ee/app/assets/stylesheets/pages/service_desk.scss

 .service-desk-issues {
   .empty-state {
-    max-width: 550px;
+    max-width: 450px;
     text-align: center;
-
-    .service-desk-graphic {
-
-    }
   }
 
   .non-empty-state {