There are too many error logs in the UT.

[workingloong]

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/logging/__init__.py", line 1088, in emit
    stream.write(msg + self.terminator)
ValueError: I/O operation on closed file.
Call stack:
  File "/usr/local/lib/python3.8/threading.py", line 890, in _bootstrap
    self._bootstrap_inner()
  File "/usr/local/lib/python3.8/threading.py", line 932, in _bootstrap_inner
    self.run()
  File "/usr/local/lib/python3.8/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/github/workspace/dlrover/python/elastic_agent/diagnosis/diagnosis_agent.py", line 251, in _periodically_report
    self.send_heartbeat()
  File "/github/workspace/dlrover/python/elastic_agent/diagnosis/diagnosis_agent.py", line 243, in send_heartbeat
    action = self._client.report_heart_beat(ts)
  File "/github/workspace/dlrover/python/elastic_agent/master_client.py", line 250, in report_heart_beat
    response: grpc.HeartbeatResponse = self._get(message)
  File "/github/workspace/dlrover/python/elastic_agent/master_client.py", line 43, in wrapper
    for i in range(retry):