Error logging from fn_api_runners

[Ning Kang]

Hi,

I just observed some error level loggings like these:
```
ERROR:apache_beam.runners.portability.fn_api_runner:created 1 workers
{'worker_5':
<apache_beam.runners.portability.fn_api_runner.EmbeddedWorkerHandler object
at 0x127fdaa58>}
ERROR:apache_beam.runners.portability.fn_api_runner:created 1 workers
{'worker_5':
<apache_beam.runners.portability.fn_api_runner.EmbeddedWorkerHandler object
at 0x127fdaa58>}
ERROR:apache_beam.runners.portability.fn_api_runner:created 1 workers
{'worker_5':
<apache_beam.runners.portability.fn_api_runner.EmbeddedWorkerHandler object
at 0x127fdaa58>}
ERROR:apache_beam.runners.portability.fn_api_runner:created 1 workers
{'worker_5':
<apache_beam.runners.portability.fn_api_runner.EmbeddedWorkerHandler object
at 0x127fdaa58>}
```
It's coming from this PR
<https://github.com/apache/beam/commit/921a9a83a156eb6af500ace1e44b91821ad426b1#diff-adf22e1eb39b451e73d4541052a33686R2015>
.
```

def get_worker_handlers(
    self,
    environment_id,  # type: Optional[str]
    num_workers  # type: int
):
  # type: (...) -> List[WorkerHandler]
  if environment_id is None:
    # Any environment will do, pick one arbitrarily.
    environment_id = next(iter(self._environments.keys()))
  environment = self._environments[environment_id]

  # assume all environments except EMBEDDED_PYTHON use gRPC.
  if environment.urn == python_urns.EMBEDDED_PYTHON:
    # special case for EmbeddedWorkerHandler: there's no need for a gRPC
    # server, but to pass the type check on WorkerHandler.create() we
    # make like we have a GrpcServer instance.
    self._grpc_server = cast(GrpcServer, None)
  elif self._grpc_server is None:
    self._grpc_server = GrpcServer(
        self._state, self._job_provision_info, self)

  worker_handler_list = self._cached_handlers[environment_id]
  if len(worker_handler_list) < num_workers:
    for _ in range(len(worker_handler_list), num_workers):
      worker_handler = WorkerHandler.create(
          environment,
          self._state,
          self._job_provision_info,
          self._grpc_server)
      _LOGGER.info(
          "Created Worker handler %s for environment %s",
          worker_handler,
          environment)
      self._cached_handlers[environment_id].append(worker_handler)
      self._workers_by_id[worker_handler.worker_id] = worker_handler
      worker_handler.start_worker()
  _LOGGER.error("created %s workers %s", num_workers, self._workers_by_id)
  return self._cached_handlers[environment_id][:num_workers]

```
Is this supposed to be an info level logging?

Thanks!

Ning.