Update AdminTranslationsController.php

[-] BO : FixBug #PSCFV-10325 - No field to translate in translations>front office
Replace "?|" syntax for preg_match_all because on some server (PHPv5.3.3) this syntax is unknow and we got this error :

[error] PHP Warning:  preg_match_all() [<a href='function.preg-match-all'>function.preg-match-all</a>]: Compilation failed: unrecognized character after (? at offset 10 in /htdocs/controllers/admin/AdminTranslationsController.php on line 1104