[fix][broker] Add double-check for non-durable cursor creation

[nodece]

Motivation

In race conditions, multiple threads could attempt to create the same non-durable cursor simultaneously.

Adding a double-check ensures that if a cursor is already created by another thread while waiting in the synchronized block, the existing cursor is returned instead of creating a new one. This preserves thread safety and avoids duplicate cursor creation.

Modifications

• Added a double-check inside the existing synchronized block for non-durable cursor creation.

Documentation

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

[nodece]

/pulsarbot rerun-failure-checks

[codecov-commenter]

Codecov Report

❌ Patch coverage is 66.66667% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.26%. Comparing base (34f8657) to head (fa50bd4).
⚠️ Report is 211 commits behind head on master.

Files with missing lines	Patch %	Lines
...che/bookkeeper/mledger/impl/ManagedLedgerImpl.java	66.66%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #24643      +/-   ##
============================================
- Coverage     74.32%   74.26%   -0.07%     
+ Complexity    33180    33155      -25     
============================================
  Files          1882     1882              
  Lines        146855   146862       +7     
  Branches      16867    16869       +2     
============================================
- Hits         109152   109063      -89     
- Misses        29038    29124      +86     
- Partials       8665     8675      +10     

Flag	Coverage Δ
inttests	26.76% <33.33%> (-0.03%)	⬇️
systests	23.28% <33.33%> (-0.16%)	⬇️
unittests	73.74% <66.66%> (-0.07%)	⬇️

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

Files with missing lines	Coverage Δ
...che/bookkeeper/mledger/impl/ManagedLedgerImpl.java	81.08% <66.66%> (-0.11%)	⬇️

... and 82 files with indirect coverage changes

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[dao-jun]

LGTM