[FEATURE] Add more integ tests for exporter and reader

[ansjcy]

Is your feature request related to a problem?

Exporters and readers are critical components in Query Insights that require robust testing coverage. Recent incidents during release have shown gaps in our testing strategy. We've encountered several unforeseen blockers during releases due to errors in exporter logic. Notable examples include:

• [BUG] Local index default setting is not working #232
• Issues mentioned in Refactor Exporters and Readers #210

The impact is big, including but not limited to:

• Release delays
• Required manual intervention
• Potential reliability issues in production
• Increased burden on manual testing before merges

Ideally, we should have extensive integ tests for such critical component to avoid manual testing before merging changes.

What solution would you like?

Have extensive integ tests for exporters and readers

• Validate core functionality
• Test edge cases
• Ensure reliability across different scenarios
• Reduce dependency on manual testing
• Prevent regression issues

What alternatives have you considered?

N/A

Do you have any additional context?

Add any other context or screenshots about the feature request here.