Backfill entity_type in evaluation_rule_entities

[dmjb]

This change backfills the entity_type column and makes it non nullable. The DB query used for listing evaluation history is also changed to use this column.

Summary

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Fixes #(related issue)

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• Bug fix (resolves an issue without affecting existing features)
• Feature (adds new functionality without breaking changes)
• Breaking change (may impact existing functionalities or require documentation updates)
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Review Checklist:

• Reviewed my own code for quality and clarity.
• Added comments to complex or tricky code sections.
• Updated any affected documentation.
• Included tests that validate the fix or feature.
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[coveralls]

coverage: 54.626% (-0.001%) from 54.627%
when pulling 4ad5053 on migrate-entity-type
into c7a8e15 on main.