[improve][admin] Add client side looping to analyze-backlog in Topics to avoid potential HTTP call timeout

[oneby-wang]

Fixes #25083

Motivation

Use client-side looping instead of increasing broker settings to avoid potential HTTP call timeout in analyze-backlog method of Topics.

Modifications

Add client-side looping, add test.

Verifying this change

• Make sure that the change passes the CI checks.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• 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

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: oneby-wang#22

[Copilot]

Pull request overview

This PR adds client-side looping to the analyzeSubscriptionBacklog method to avoid HTTP call timeouts when analyzing large backlogs. Instead of relying solely on broker-side configuration limits, the client can now iteratively call the analyze-backlog endpoint and merge results until completion or a specified entry limit is reached.

• Adds new overloaded methods with a backlogScanMaxEntries parameter to control client-side loop termination
• Implements iterative scanning logic that merges results from multiple server calls
• Includes comprehensive integration tests covering various scenarios
• Modifies OpScan behavior by removing individual deleted entry filtering

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 8 comments.

File	Description
pulsar-client-admin-api/src/main/java/org/apache/pulsar/client/admin/Topics.java	Adds new API methods with backlogScanMaxEntries parameter and detailed JavaDoc documentation
pulsar-client-admin/src/main/java/org/apache/pulsar/client/admin/internal/TopicsImpl.java	Implements client-side looping logic with result merging and next position calculation
pulsar-broker/src/test/java/org/apache/pulsar/broker/admin/AnalyzeBacklogSubscriptionTest.java	Adds comprehensive integration tests for the new looping behavior
managed-ledger/src/main/java/org/apache/bookkeeper/mledger/impl/OpScan.java	Removes filterReadEntries call and adjusts entry counting logic

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[lhotari]

A few comments. I'm sorry for the delay in the review.

[lhotari]

A few comments about the existing log messages. I think it makes sense to change them in this PR since after this PR, it would be an ordinary use case to scan larger backlogs.

[lhotari]

LGTM. Great work @oneby-wang

[oneby-wang]

Thanks for your great suggestions! @lhotari