[fix] [broker] fix NPE when calculating a topic's backlogQuota

[poorbarcode]

Motivation

Background
The steps for checking backlog metadata are as follows

• Get the oldest cursor
• Return the result if the oldest cursor.md equals LAC
• Else, calculate the estimated backlog quota

Issue

• The method PersistentTopic.estimatedTimeBasedBacklogQuotaCheck may get an NPE when the @param position(cursor.markDeletedPositon) equals LAC and the latest ledger has been removed by a ML.trimLedgers, which was introduced by [feat][broker] Implementation of PIP-323: Complete Backlog Quota Telemetry #21816
• Q: The broker checked whether the oldest cursor.md equals LAC at step 2 above, why does it still call PersistentTopic.estimatedTimeBasedBacklogQuotaCheck with a param that equals LAC?
  • A: There may be some acknowledgments and ML.trimLedgers that happened between step2 above and step 3 above

Modifications

• Fix NPE, and let the logic is the same as the behavior before [feat][broker] Implementation of PIP-323: Complete Backlog Quota Telemetry #21816

Documentation

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

Matching PR in forked repository

PR in forked repository: x

[poorbarcode]

/pulsarbot rerun-failure-checks

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.43%. Comparing base (bbc6224) to head (a6ce58a).
Report is 788 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23720      +/-   ##
============================================
+ Coverage     73.57%   74.43%   +0.85%     
- Complexity    32624    35110    +2486     
============================================
  Files          1877     1945      +68     
  Lines        139502   147482    +7980     
  Branches      15299    16278     +979     
============================================
+ Hits         102638   109775    +7137     
- Misses        28908    29244     +336     
- Partials       7956     8463     +507     

Flag	Coverage Δ
inttests	27.29% <0.00%> (+2.71%)	⬆️
systests	24.33% <0.00%> (+0.01%)	⬆️
unittests	73.82% <100.00%> (+0.97%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...sar/broker/service/persistent/PersistentTopic.java	80.02% <100.00%> (+1.56%)	⬆️

... and 667 files with indirect coverage changes

[liamgib]

Hi there, when will this fix be included in the next release?

[lhotari]

@poorbarcode Would you mind cherry-picking this to branch-3.0 and branch-3.3? Thanks

[poorbarcode]

@poorbarcode Would you mind cherry-picking this to branch-3.0 and branch-3.3? Thanks

Done