Fix operator tests for transient null TsBlocks

[Caideyipi]

Description

Backport #17838 to dev/1.3.

Cherry-picked from 16d3669 with branch-specific conflict resolution for 1.3 operator test class names/packages.

Checks

• mvn -DskipTests spotless:check -pl iotdb-core/datanode
• mvn -pl iotdb-core/datanode '-Dtest=AlignedSeriesAggregationScanOperatorTest,FillOperatorTest,HorizontallyConcatOperatorTest,LinearFillOperatorTest,MergeSortOperatorTest,OffsetOperatorTest,SeriesAggregationScanOperatorTest,SeriesScanOperatorTest,UpdateLastCacheOperatorTest' test (blocked before tests by existing datanode compile errors in unrelated schemaengine/pipe/subscription classes)

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
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 42.56%. Comparing base (0288aab) to head (ad2a864).

Additional details and impacted files

@@            Coverage Diff             @@
##             dev/1.3   #17847   +/-   ##
==========================================
  Coverage      42.55%   42.56%           
  Complexity       241      241           
==========================================
  Files           3621     3621           
  Lines         240247   240247           
  Branches       29263    29263           
==========================================
+ Hits          102243   102253   +10     
+ Misses        138004   137994   -10     

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