Can not exit the RedisCluster client after redis-server is down

[suxb201]

Version and Platform:

• Darwin Kernel Version 21.6.0
• Python 3.10.4
• redis-py 4.4.0rc1

Description:
After redis is down, you can not exit the redis-cluster client

16:17:46.524 error occurred when writing data: ERROR sending "cluster slots" command to redis server 127.0.0.1:30008. error: cannot pickle '_thread.lock' object
Exception ignored in: <function ClusterNode.__del__ at 0x7f79d9e03640>
Traceback (most recent call last):
  File "/opt/miniconda3/envs/py310/lib/python3.10/site-packages/redis/cluster.py", line 1191, in __del__
    if self.redis_connection is not None:
AttributeError: 'ClusterNode' object has no attribute 'redis_connection'
Exception ignored in: <function ClusterNode.__del__ at 0x7f79d9e03640>
Traceback (most recent call last):
  File "/opt/miniconda3/envs/py310/lib/python3.10/site-packages/redis/cluster.py", line 1191, in __del__
    if self.redis_connection is not None:
AttributeError: 'ClusterNode' object has no attribute 'redis_connection'
Exception ignored in: <function ClusterNode.__del__ at 0x7f79d9e03640>
Traceback (most recent call last):
  File "/opt/miniconda3/envs/py310/lib/python3.10/site-packages/redis/cluster.py", line 1191, in __del__
    if self.redis_connection is not None:
AttributeError: 'ClusterNode' object has no attribute 'redis_connection'

[dvora-h]

Fixed in #2377