CSS: Use icon-info-circled for form control help

refs #5543

library/Icinga/Web/Form/Decorator/Help.php

@@ -94,10 +94,10 @@ class Help extends Zend_Form_Decorator_Abstract
             }
 
             $helpContent = $this->getView()->icon(
-                'help',
+                'info-circled',
                 $description . ($description && $requirement ? ' ' : '') . $requirement,
                 array(
-                    'class'         => 'help',
+                    'class'         => 'control-info',
                     'aria-hidden'   => $this->accessible ? 'true' : 'false'
                 )
             ) . $helpContent;