Added flags to mark whether a device has device descendants to optimize query like select xx from xxx.**

[Caideyipi]

Description

As the title said.

---

This PR has:

• been self-reviewed.
  • concurrent read
  • concurrent write
  • concurrent read and write
• added documentation for new or modified features or behaviors.
• added Javadocs for most classes and all non-trivial methods.
• added or updated version, license, or notice information
• added comments explaining the "why" and the intent of the code wherever would not be obvious
  for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold
  for code coverage.
• added integration tests.
• been tested in a test IoTDB cluster.

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Key changed/added classes (or packages if there are too many classes) in this PR

[codecov]

Codecov Report

❌ Patch coverage is 93.85475% with 11 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.43%. Comparing base (556cd66) to head (49071fd).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
...engine/schemaregion/mtree/traverser/Traverser.java	90.56%	5 Missing ⚠️
...aregion/mtree/impl/mem/MTreeBelowSGMemoryImpl.java	95.00%	2 Missing ⚠️
...impl/pbtree/mnode/impl/CachedMeasurementMNode.java	66.66%	2 Missing ⚠️
...gion/mtree/impl/pbtree/MTreeBelowSGCachedImpl.java	97.67%	1 Missing ⚠️
...pl/pbtree/mnode/impl/CachedAboveDatabaseMNode.java	83.33%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #17672      +/-   ##
============================================
+ Coverage     40.38%   40.43%   +0.05%     
  Complexity     2574     2574              
============================================
  Files          5178     5178              
  Lines        349134   349328     +194     
  Branches      44665    44697      +32     
============================================
+ Hits         140988   141252     +264     
+ Misses       208146   208076      -70     

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[luoluoyuyu]

Review summary

Adds hasDeviceDescendant flags on schema nodes and maintains them when creating devices and when deleting empty internal nodes. This should speed up queries that need to know if a prefix has device descendants.

Please fix CI failures and add tests for flag updates on delete/move paths touched in this PR.

[luoluoyuyu]

setToEntityAndUpdateFlags marks ancestors when a node becomes a device. Please confirm refreshAncestorsHavingDeviceDescendant on deleteEmptyInternalMNode keeps flags correct when the last device under a prefix is removed.

[Caideyipi]

Confirmed and covered with tests. The delete refresh recomputes ancestors from children, so when the last device under one prefix is removed, higher ancestors stay true if another sibling device subtree still exists and become false only after the last remaining device subtree is removed. I extended both memory and cached MTree tests for that case, and added memory-mode table-device drop coverage as well.

[Caideyipi]

Addressed the review comments in commit 2a68c38:

• Made IMNodeIterator AutoCloseable and converted the new iterator scans to try-with-resources.
• Reduced the Sonar duplication from repeated flag delegate methods by moving the shared accessors to default methods on IMemMNode / ICachedMNode.
• Added coverage for delete refresh correctness when one device subtree is removed while another sibling device subtree still exists, plus table-device drop coverage in memory mode.

Verification:

• mvn -pl iotdb-core/datanode,iotdb-core/node-commons spotless:apply
• MAVEN_OPTS=-Xmx768m mvn -Ddevelocity.off=true -Dcheckstyle.skip=true -Dspotless.check.skip=true -pl iotdb-core/node-commons,iotdb-core/datanode -Dtest=MTreeBelowSGMemoryImplTest,MTreeBelowSGCachedImplTest -DfailIfNoTests=false -Dsurefire.failIfNoSpecifiedTests=false test

For current CI: the latest failing Simple (17) job failed during �ctions/checkout with a GitHub TLS fetch error before build/test. The dual-tree-auto-basic failure is in IoTDBPipeLifeCycleIT.testLifeCycleLogMode, unrelated to this schema flag change.

[sonarqubecloud]

Quality Gate passed

Issues
4 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
1.8% Duplication on New Code

See analysis details on SonarQube Cloud