Consolidate LLC Kafka ingestion integration tests

[xiangfu0]

Summary

• run the full LLC recovery and query-conformance suite once with the canonical Kafka 3 consumer
• replace the duplicate Kafka 4 full-suite class with a focused Kafka 4 scenario that injects consumer-creation and fetch failures, verifies OFFLINE transitions and validation-manager recovery, then checks all 115,545 rows
• remove the now-identical Kafka 3 subclass

This reduces three full Pinot/Kafka cluster lifecycles and 57 TestNG invocations to one lifecycle and 20 invocations. It keeps the existing two integration-test CI jobs unchanged.

Validation

• LLCRealtimeClusterIntegrationTest: 20 invocations, 0 failures, 0 errors, 2 existing skips, 200.1 s locally
• focused Kafka 4 failure/recovery scenario: 50.35 s locally
• representative master CI baseline for the three classes: 827.4 s total
• pinot-integration-tests test-compile
• Spotless, Checkstyle, license format/check, and git diff check
• independent correctness review after preserving Kafka 4 failure coverage and Throwable-safe cleanup

The draft PR CI is intended to validate the hosted runtime delta.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 66.62%. Comparing base (baaf0a7) to head (8fec45a).

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #19194   +/-   ##
=========================================
  Coverage     66.62%   66.62%           
  Complexity     1423     1423           
=========================================
  Files          3443     3443           
  Lines        218626   218626           
  Branches      34792    34792           
=========================================
+ Hits         145662   145664    +2     
- Misses        61240    61243    +3     
+ Partials      11724    11719    -5     

Flag	Coverage Δ
custom-integration1	100.00% <ø> (ø)
integration	100.00% <ø> (ø)
integration1	100.00% <ø> (ø)
integration2	0.00% <ø> (ø)
java-25	66.62% <ø> (+<0.01%)	⬆️
temurin	66.62% <ø> (+<0.01%)	⬆️
unittests	66.62% <ø> (+<0.01%)	⬆️
unittests1	57.19% <ø> (-0.01%)	⬇️
unittests2	38.91% <ø> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[xiangfu0]

Folded into #19190.