Wait for the RabbitMQ process to be come up.

def wait_for_start(self):
        """
        Wait for the RabbitMQ process to be come up.
        """
        er = self.exec_rabbitmqctl(
            'wait', ['--pid', '1', '--timeout', str(int(self.wait_timeout))])
        output_lines(er, error_exc=TimeoutError)