refactor(port): unhardcode oter_id migrations

[Vollch]

Purpose of change

Getting rid of hardcoded legacy, and allowing easier migration

Describe the solution

Ported:

• Unhardcode oter_id migrations CleverRaven/Cataclysm-DDA#64564

Describe alternatives you've considered

Testing

Added new oter to json, and successfully migrated it

Additional context

Checklist

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[scarf005]

LGTM.