Flaky test for auto_close_connection_pool

[aiven-sal]

Test test_connection.py:test_valkey_connection_pool randomly fails (e.g. https://github.com/valkey-io/valkey-py/actions/runs/12349111084/job/34459287816 )
I think this may actually be a bug in valkey-py, and not just a testing issue.
But it needs further investigations.