Fix concurrent access during TierManager folder reset

[jt2594838]

Description

• build replacement tier folder-manager lists and directory-to-tier maps locally before publishing them
• publish initialized list and map references with volatile visibility instead of clearing live collections
• add a concurrent regression test covering sequence, unsequence, object, COPY TO, folder-manager, tier-count, folder-list, and file-tier accessors

Tests

• mvn test -pl iotdb-core/datanode -Dtest=TierManagerTest
• mvn test -pl iotdb-core/datanode -Dtest=IoTDBSnapshotTest
• mvn compile -pl iotdb-core/datanode -DskipTests

[Caideyipi]

[P1] Build and publish the directory maps with the tier lists seqDir2TierLevel and unSeqDir2TierLevel are still cleared and repopulated in place while their readers are unsynchronized. During loadHotModifiedProps(), readers such as getAllFilesFolders() can observe an empty or partial map, while getFileTierLevel() can race with HashMap mutation and throw ConcurrentModificationException. Please build replacement maps locally and publish them together with the folder-manager lists, and cover these accessors in the regression test.

[jt2594838]

Included these maps in initFolders.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 42.75%. Comparing base (f1875ed) to head (3af496a).
⚠️ Report is 12 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #18223      +/-   ##
============================================
+ Coverage     42.40%   42.75%   +0.34%     
  Complexity      343      343              
============================================
  Files          5354     5356       +2     
  Lines        379174   380160     +986     
  Branches      49149    49317     +168     
============================================
+ Hits         160803   162536    +1733     
+ Misses       218371   217624     -747     

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[sonarqubecloud]

Quality Gate failed

Failed conditions
B Reliability Rating on New Code (required ≥ A)

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