Switch FieldValidationRule plugins to the Provider Configuration Form Element

[Tracker]
Update Summary: [One-line status update for stakeholders]
Short Description: Replace the custom provider/model selectors in the AI Validations FieldValidationRule plugins with the Provider Configuration Form Element, with default models enabled.
Check-in Date: MM/DD/YYYY
[/Tracker]

Problem/Motivation

The AI Validations module currently rolls its own provider/model selection UI in each FieldValidationRule plugin that doesn't allow for default model, making recipes hard. The AI module now ships a reusable Provider Configuration Form Element that handles this consistently, including default model selection. See AI Provider Configuration Form Element.

Proposed resolution

• Switch AiTextConstraintFieldValidationRule to the Provider Configuration Form Element.
• Switch AiImageConstraintFieldValidationRule to the Provider Configuration Form Element.
• Switch AiImageClassificationConstraintFieldValidationRule to the Provider Configuration Form Element.
• Enable default models on the element so each rule falls back to the site's configured default.

AI usage (if applicable)

[x] AI Assisted Issue
This issue was generated with AI assistance, but was reviewed and refined by the creator.

[ ] AI Assisted Code
[ ] AI Generated Code
[ ] Vibe Coded

- This issue was created with the help of AI