Start the log monitor.

def start_log_monitor(self):
        """Start the log monitor."""
        stdout_file, stderr_file = self.new_log_files("log_monitor")
        process_info = ray.services.start_log_monitor(
            self.redis_address,
            self._logs_dir,
            stdout_file=stdout_file,
            stderr_file=stderr_file,
            redis_password=self._ray_params.redis_password)
        assert ray_constants.PROCESS_TYPE_LOG_MONITOR not in self.all_processes
        self.all_processes[ray_constants.PROCESS_TYPE_LOG_MONITOR] = [
            process_info
        ]