[fix][broker] Fix exclusive producer creation when last shared producer closes

[3pacccccc]

Motivation

When a producer in WaitForExclusive mode is created while shared producers exist on a topic, it fails to become active even after all shared producers are closed. This occurs because the broker doesn't properly check for waiting exclusive producers when the last shared producer is removed.

Steps to reproduce:

1. Create a producer with Shared mode
2. Create a producer with WaitForExclusive mode
3. Close the first producer
4. The exclusive producer never gets created

Modifications

• Modified the condition in handleProducerRemoved() to also check for waiting exclusive producers when the last producer is removed
• Added test case to verify the fix

Verifying this change

• Make sure that the change passes the CI checks.

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: 3pacccccc#13

[lhotari]

LGTM, good work @3pacccccc

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.30%. Comparing base (bbc6224) to head (d1645a6).
Report is 1217 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24516      +/-   ##
============================================
+ Coverage     73.57%   74.30%   +0.73%     
+ Complexity    32624    32583      -41     
============================================
  Files          1877     1874       -3     
  Lines        139502   146231    +6729     
  Branches      15299    16772    +1473     
============================================
+ Hits         102638   108662    +6024     
- Misses        28908    28935      +27     
- Partials       7956     8634     +678     

Flag	Coverage Δ
inttests	26.84% <0.00%> (+2.26%)	⬆️
systests	23.26% <0.00%> (-1.07%)	⬇️
unittests	73.81% <100.00%> (+0.96%)	⬆️

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

Files with missing lines	Coverage Δ
...rg/apache/pulsar/broker/service/AbstractTopic.java	88.18% <100.00%> (+0.19%)	⬆️

... and 1107 files with indirect coverage changes

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