MDL-39077 max_files does not include current option when it is non-standard

Non-standard means php.ini was set to something not in the default list (like 7MB),
then the config was saved to that specific value, and now the value in php.ini has been changed
again so 7MB does not appear in the list.

admin/settings/security.php

@@ -23,9 +23,8 @@ if ($hassiteconfig) { // speedup for non-admins, add all caps used on this page
         new lang_string('configprofileroles', 'admin'),
         array('student', 'teacher', 'editingteacher')));
 
-    $max_upload_choices = get_max_upload_sizes();
+    $max_upload_choices = get_max_upload_sizes(0, 0, 0, $CFG->maxbytes);
     // maxbytes set to 0 will allow the maximum server limit for uploads
-    $max_upload_choices[0] = new lang_string('serverlimit', 'admin');
     $temp->add(new admin_setting_configselect('maxbytes', new lang_string('maxbytes', 'admin'), new lang_string('configmaxbytes', 'admin'), 0, $max_upload_choices));
     // 100MB
     $defaultuserquota = 104857600;