chore(query): null first behavior

[sundy-li]

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Summary

1. Add settings default_order_by_null defaults to nulls_last.

PG and snowflake use default value nulls_last_on_asc_first_on_desc.

If we change the default value to nulls_last_on_asc_first_on_desc, it's the same as PG but incompatible with the previous version.

2. Also fix a bug in stats from external parquet file.

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