[to dev/1.3] Fix query reuse of flushing memtable TVList

[shuwenwei]

What changed

• Avoid reusing an unsorted mutable working TVList for flushing-memtable queries when another query may still be reading the original list.
• Use the working list for flush when the flushing query cannot safely reuse the original TVList.
• Keep the original list bound to the query context because the flush working list can share value arrays with it.
• Add regression coverage for the Q1/Q2/FLUSH ordering that could previously reorder indices behind Q1's stale row-count view.

Why

Q1 may query the working memtable and record a smaller visible row count. Later out-of-order writes append to the same TVList, then FLUSH moves the memtable to flushing. If Q2 queries the flushing memtable and sorts the original mutable TVList in place, Q1 may continue reading with old rows but reordered indices, causing bitmap index out-of-bound.

Validation

• Added PrimitiveMemTableTest#testFlushingQueryDoesNotSortWorkingTVListUsedByPreviousQuery

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 42.10%. Comparing base (fea9a2f) to head (b30181c).

Additional details and impacted files

@@              Coverage Diff              @@
##             dev/1.3   #17709      +/-   ##
=============================================
- Coverage      42.10%   42.10%   -0.01%     
  Complexity       241      241              
=============================================
  Files           3613     3613              
  Lines         238738   238749      +11     
  Branches       29001    29003       +2     
=============================================
- Hits          100525   100519       -6     
- Misses        138213   138230      +17     

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