Finalize troubleshoot job claude 3.7 upgrade

What does this MR do and why?

Finalize troubleshoot job claude 3.7 upgrade

Follow-up of AI Gateway: gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2679 (merged)

Part of this 2-step plan: #545699 (comment 2543533261)

How to set up and validate locally

Ensure AI is setup via https://docs.gitlab.com/development/code_suggestions/#setup-instructions-to-use-gdk-with-the-code-suggestions-add-on

Ensure FF **Feature.enable(:prompt_migration_troubleshoot_job) is enabled.

Triggering /troubleshoot from a failed job should write the model it's using via the AI Gateway logs.

MR acceptance checklist

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