Remove reference to bootstrap alert

- alert class is used with bootstrap
- remove missed class reference

app/views/projects/tracings/show.html.haml

@@ -3,7 +3,7 @@
 
 - if @project.tracing_external_url.present?
   %h3.page-title= _('Tracing')
-  .gl-alert.gl-alert-info.alert.flex-alert
+  .gl-alert.gl-alert-info.gl-mb-5.flex-alert
     = sprite_icon('information-o', css_class: 'gl-icon gl-alert-icon gl-alert-icon-no-title')
     .alert-message
       = _("Your password isn't required to view this page. If a password or any other personal details are requested, please contact your administrator to report abuse.")