[Python] Fix flaky test test_tls_with_multiple_certificates_succeeds #4950

[hank95179]

Issue link

This Pull Request is linked to issue (URL): #4950

Description

This PR addresses the flakiness observed in test_tls_with_multiple_certificates_succeeds.
Similar to issue #4946, the TLS handshake process occasionally times out in high-load environments (such as CI/CD) due to resource contention, leading to ClosingError: ... timed out failures.

Solution

Implemented a retry mechanism for client creation in tests/async_tests/test_tls_certificates.py.

• Implemented a retry mechanism for client creation in tests/async_tests/test_tls_certificates.py.
  The test now attempts to establish the connection up to 3 times with an exponential backoff (2^i seconds) before failing.
• Applied this logic to both Cluster and Standalone modes to ensure stability.

Verification

Verified that the retry mechanism correctly handles transient connection failures, allowing the test to pass in environments with varying latency.

[xShinnRyuu]

In your description under Solution you say the fix has a 1-second backoff. Your implementation uses time.sleep(2**i) within your retry loop, which is a duration equal to 2 raised to the power of i seconds.

I'm unsure if that is what was intended but an exponential backoff is usually the norm for retry. Ideally, its a not that high of an exponential, because if there were more retires it would take a very long time. But three retries is fine here with base 2 exponential.

Please update your description, or adjust your implementation. Otherwise, it generally looks good.

[hank95179]

@xShinnRyuu Thank you! I've updated the description.

[xShinnRyuu]

LGTM

[currantw]

Approved with one suggestion. Thanks for helping with this!

[currantw]

Nit. Might be worth extracting to a helper and adding a comment explaining why this retry mechanism is needed.