chore: fix window plan in lazy topn

[sundy-li]

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Summary

fix window plan in lazy topn

• Fixes bug: Unable to get field named "5". Valid fields: ["2", "3", "10"] #15157

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):

[sundy-li]

I found better way to handle this, see the lastest commit.