[Fix] Preserve query memory registrations during stale fragment cleanup

[JackieTien97]

Description

A delayed fragment cleanup can retain an old query-memory map while another fragment removes the last registration and a later fragment creates a replacement map. Removing the outer entry by query ID alone then deletes the replacement, causing MemoryPool.free() to fail when buffered results are consumed.

Only remove the outer entry when it still references the map being cleaned up. The identity check stays inside the existing registration lock, while memory-usage checks remain outside it.

Add a deterministic concurrent regression test that pauses an empty fragment's cleanup at the registration lock, replaces the query map, and verifies that the new reservation survives and can be freed. Additional tests cover missing fragments, other active fragments, deferred and repeated cleanup, and forced memory-leak reporting.

Validation

• Before the production fix, the new concurrent test fails with expected:<1> but was:<0> because the replacement registration is removed.
• English full-reactor build with focused unit tests passed: MemoryPoolTest (27 tests) and SharedTsBlockQueueTest (2 tests).
  • mvn clean test -Dtest=MemoryPoolTest,SharedTsBlockQueueTest -Dsurefire.failIfNoSpecifiedTests=false -DfailIfNoTests=false
• Chinese full-reactor compilation passed:
  • mvn test-compile -DskipTests -P with-zh-locale
• IoTDBTableViewQueryIT passed all four aligned/flush combinations in a clean worktree:
  • mvn clean verify -DskipUTs -Dit.test=IoTDBTableViewQueryIT -DfailIfNoTests=false -Dfailsafe.failIfNoSpecifiedTests=false -DDataNodeMaxHeapSize=1024 -DintegrationTest.forkCount=1 -pl integration-test -am -P with-integration-tests -P TableSimpleIT
• Spotless formatting and git diff --check passed.

Checklist

• Self-reviewed concurrent registration and deregistration.
• Added comments explaining the identity check.
• Added unit tests for the race and cleanup semantics.
• Tested the affected query path in an IoTDB test cluster.

Key changed classes

• MemoryPool
• MemoryPoolTest

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.90%. Comparing base (5c27559) to head (b0b96f6).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18834      +/-   ##
============================================
- Coverage     45.91%   45.90%   -0.01%     
  Complexity      712      712              
============================================
  Files          5502     5502              
  Lines        398764   398776      +12     
  Branches      51963    51968       +5     
============================================
- Hits         183090   183070      -20     
- Misses       215674   215706      +32     

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