[improve][client]:Perform health checks on the endpoints that passed in by serviceUrl of PulsarClient

[AuroraTwinkle]

Main Issue: https://github.com/apache/pulsar/issues/22934

Motivation

Refer to issue: https://github.com/apache/pulsar/issues/22934

Modifications

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This change is a trivial rework / code cleanup without any test coverage.

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

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• [ ] Dependencies (add or upgrade a dependency)
• [ ] The public API
• [ ] The schema
• [ ] The default values of configurations
• [ ] The threading model
• [ ] The binary protocol
• [ ] The REST endpoints
• [ ] The admin CLI options
• [ ] The metrics
• [ ] Anything that affects deployment

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Matching PR in forked repository

PR in forked repository: https://github.com/AuroraTwinkle/pulsar/pull/4

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[AuroraTwinkle]

@liangyepianzhou I have fixed all your comments, PTAL, thanks

[lhotari]

Replied in https://github.com/apache/pulsar/issues/22934#issuecomment-2943690398 about a better way to solve the actual problem.

[AuroraTwinkle]

The general design is problematic since the health checking will keep running and creating TCP/IP connections that are immediately closed. This will cause additional load in the overall system, including endpoints (proxies / brokers). Additionally opening and closing a TCP/IP connection will keep the local port occupied in TIME_WAIT state for some time (2*MSL, 60s-240s depending on OS and it's config). SO_REUSEADDR/SO_REUSEPORT doesn't prevent port occupation since it doesn't help bypass TIME_WAIT restrictions for outbound client connections to the same 4-tuple (local ip, local port, remote ip, remote port).

Before actually implementing this health check feature, it would be necessary to describe the issue that is currently caused by not adding the health check and primary addressing that issue instead of implementing this solution in this PR.

Ok, I will start a new PR for a better solution that mentioned at https://github.com/apache/pulsar/issues/22934#issuecomment-2943690398. And I will close current PR.