correctly use i18n in EE specific project menu points

ee/app/views/projects/sidebar/_issues_service_desk.html.haml

@@ -2,4 +2,4 @@
 
 = nav_link(controller: :issues, action: :service_desk ) do
   = link_to service_desk_project_issues_path(@project), title: 'Service Desk' do
-    %span _('Service Desk')
+    = _('Service Desk')

ee/app/views/projects/sidebar/_settings_audit_events.html.haml

@@ -2,4 +2,4 @@
 
 = nav_link(controller: :audit_events) do
   = link_to project_audit_events_path(@project), title: "Audit Events" do
-    %span _('Audit Events')
+    = _('Audit Events')