Fix error when contacts folder contains non-alphanum chars (Bifrost#T245789)

By removing outdated and redundant check.

plugins/kolab_addressbook/kolab_addressbook.php

@@ -407,12 +407,6 @@ class kolab_addressbook extends rcube_plugin
     {
         if ($p['id']) {
             $id     = kolab_storage::id_decode($p['id']);
-
-            // check for falsely base64 decoded identifier
-            if (preg_match('![^A-Za-z0-9=/+&._ -]!', $id)) {
-                $id = $p['id'];
-            }
-
             $folder = kolab_storage::get_folder($id);
 
             // try with unencoded (old-style) identifier