fixes #2417 ability to hide the new filter "expert mode"

... and removes 2 other duplicates of the filters_views configuration

include/config_default.inc.php

@@ -1054,6 +1054,7 @@ $conf['default_filters_views'] = array(
   'file_size'      => ['access'=>'everybody', 'default'=>false],
   'height'         => ['access'=>'everybody', 'default'=>false],
   'width'          => ['access'=>'everybody', 'default'=>false],
+  'expert'         => ['access'=>'everybody', 'default'=>false],
 
   'last_filters_conf' => true,
 );