fix(query): NULL constraint checking in column modification

[TCeason]

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Summary

rely on the underlying CAST operations to detect and report NULL constraint violations during execution.

This simplifies the code by eliminating special case handling
while maintaining the same data integrity guarantees.

Fix: #18852

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - Explain why

Type of change

• Bug Fix (non-breaking change which fixes an issue)
• New Feature (non-breaking change which adds functionality)
• Breaking Change (fix or feature that could cause existing functionality not to work as expected)
• Documentation Update
• Refactoring
• Performance Improvement
• Other (please describe):

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This change is