Log deleted-record percentages per import input

[rohitkumarbhagat]

What changed

• Add deleted-record percentage, deleted-record count, and previous observation count to validation metrics.
• Emit validation status independently for each import input.
• Include the import input identifier in each validation metric.
• Prevent malformed or unknown validation rules from causing metric logging to fail.
• Add coverage for multiple inputs with mixed validation statuses.

Tests

• Focused import executor unit test
• Google YAPF formatting check
• Python compilation
• git diff --check

[gemini-code-assist]

Code Review

This pull request enhances metric logging during import validation by extracting and reporting specific metrics (such as deleted records percentage, deleted records count, and previous observation count) when the DELETED_RECORDS_PERCENT validator is used. It also adds a comprehensive unit test to verify this behavior. The review feedback highlights two important issues: first, a potential runtime error if validation rules are malformed, which can be resolved by adding explicit type checks when parsing rules; second, a logical bug where input_validation_status is not reset to False inside the except ValueError block, potentially leading to incorrect success status logging when a validation runner fails.