[Fix] Address aligned memory accounting Sonar issues

[Caideyipi]

Description

This is a follow-up to #18330. Sonar reported 14 issues in the aligned memory accounting changes.

This PR:

• removes six redundant long casts and groups the overloaded memory-cost methods;
• normalizes TvList naming in the reconciliation snapshot and helper;
• documents and narrowly suppresses complexity in stateful write/scan hot paths, plus the tablet helper parameter count.

These changes do not alter runtime behavior.

Verification

• AlignedTVListTest: 15 passed
• TsFileProcessorTest: 20 passed
• DataNode main and related test sources compiled
• Checkstyle: 0 violations
• Spotless and git diff --check: passed

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This PR has:

• been self-reviewed.
• added comments explaining the targeted Sonar suppressions.
• been covered by existing unit tests.