Make storage alert full-width

To conform with other page-level alerts we've got

ee/app/views/shared/_namespace_storage_limit_alert.html.haml

@@ -14,9 +14,8 @@
 - icon = namespace_storage_alert_icon(alert_level)
 - link = namespace_storage_usage_link(root_namespace)
 
-%div{ class: ['js-namespace-storage-alert', [container_class, ("limit-container-width" unless fluid_layout)]] }
-  .gl-pt-5.gl-pb-3
-    .gl-alert{ class: "gl-alert-#{style}", role: 'alert' }
+.gl-py-5
+  .gl-alert.js-namespace-storage-alert{ class: "gl-alert-#{style}", role: 'alert' }
     = sprite_icon(icon, css_class: "gl-icon gl-alert-icon")
     .gl-alert-title
       %h4.gl-alert-title= payload[:usage_message]