chore: adjust row count assertion in table compaction

[dantengsky]

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Summary

Correct the assertion to check that the row count remains unchanged during table compaction, instead of comparing it(new snapshot) to the pre-compaction snapshot. This change accounts for scenarios where the new snapshot results from a combination of compaction and insertion, potentially increasing the total number of rows.

• Fixes #[Link the issue here]

Tests

• Unit Test
• Logic Test
• Benchmark Test
• No Test - only a defensive runtime assertion changed

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): only a defensive runtime assertion changed

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This change is