testing scheduled file deletions
It isn't configurable. You would be better served writing your own routine that executes on a regular interval and searches for temporary files whose creation age is greater than 10 minutes ago.
The DRUPAL_MAXIMUM_TEMP_FILE_AGE constant is specifically intended to inform Drupal on when a file that has not yet been set to permanent should be removed.
If you take a look at system.module, the relevant code is contained in a hook_cron() implementation. The code reads:
  $result = db_query('SELECT fid FROM {file_managed} WHERE status &lt;&gt; :permanent AND timestamp &lt; :timestamp', array(
    ':permanent' =&gt; FILE_STATUS_PERMANENT,
    ':timestamp' =&gt; REQUEST_TIME - DRUPAL_MAXIMUM_TEMP_FILE_AGE,
  ));

My recommendation is to simply implement your own hook_cron() and use the same code, but calculate for files older than 10 minutes.
You will also need for cron to execute on a 10 minute interval. For this, you'll need to add a crontab and install either ultimate_cron or elysisia_cron. I prefer ultimate_cron.
Please see my answer to this question for more information on setting up crontab on a 60 second interval for maximum timeliness. You'll then use elysia_cron or ultimate_cron to control the actual job execution interval.