[Instruments] Bugfix multi-escaped special characters (aces#6223)

Removed duplicate call to HTMLSpecialChars() causing double escaping on any instrument field with one of the following characters & < > "

The removal is justified since these fields are being escaped directly in the database class
https://github.com/aces/Loris/blob/master/php/libraries/Database.class.inc#L538

php/libraries/LorisForm.class.inc

@@ -695,10 +695,6 @@ class LorisForm
                 }
             }
         }
-        // Always sanitize user-controlled input
-        if (!is_array($newValue)) {
-            $newValue = htmlspecialchars($newValue);
-        }
 
         return $newValue;
     }