[fix][consumer] Use resolved partition topic for single-partition zero queue consumer

[Technoboy-]

Motivation

When a partitioned topic has exactly one partition, TopicPartitions returns the physical partition topic, e.g. topic-partition-0. However, the zero queue consumer path ignored that resolved topic and still created the internal consumer with the original base topic.

With newer brokers that enforce topic consistency, subscribing to the base topic after partitioned metadata exists is rejected with "Found partitioned metadata for non-partitioned topic". This change makes zero queue consumers use the resolved single partition topic, matching the normal consumer path and avoiding repeated failed subscribe attempts.

Modifications

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

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This change is already covered by existing tests, such as (please describe tests).

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This change added tests and can be verified as follows:

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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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[Copilot]

Pull request overview

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Fixes zero-queue consumer subscription behavior for single-partition partitioned topics by ensuring it uses the resolved physical partition topic name (e.g., *-partition-0) instead of the base topic, avoiding broker rejections due to partitioned metadata.

Changes:

• Pass the resolved single partition topic (partitions[0]) into the zero-queue consumer constructor.
• Add a unit/integration test validating the zero-queue consumer uses the resolved partition topic internally.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
pulsar/consumer_impl.go	Ensures zero-queue consumer uses the resolved single-partition topic name when partitions==1.
pulsar/consumer_zero_queue_test.go	Adds coverage asserting zero-queue consumer binds to the single physical partition topic.

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