Map ClientException to HTTP 500 in Automation ExceptionHandler to log these exceptions server-side

Since NXP-11403, ClientException are mapped to HTTP 400 in ExceptionHandler, therefore not logged by default server-side by the Jersey container in ContainerResponse#onException:

if (!mapped && r.getStatus() >= 500) {
logException(e, r, Level.SEVERE);
} else if (LOGGER.isLoggable(Level.FINE)) {
logException(e, r, Level.FINE);
}

In most of the cases, Nuxeo API will throw a ClientException that should be logged by the server, so let's map ClientException to HTTP 500.