[Fix] Multi Auth Token issue

[psriramsnc]

🐞 Bug Fix: Multi Auth Token Issue

🧾 Summary

Fixes the Multi Auth Token issue when mutliple URLs, auth_tokens are provided
Previously, models inconsistently used api_key and auth_token, leading to authentication mismatches.
This PR ensures consistent use of auth_token for all model configurations, improving reliability and maintainability.

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💡 Impacted Features:

• Multiple urls, auth tokens to a model in.env with | separator can be provided
• Added Unit test case for multi token scenario.

Minor Fixes:

• Fixed model health check issues with vllm models in UI
• Deprecated api_key for azure_openai to make it consistent with other model types. api_key -> auth_token
• Updated azure_openai test cases to be in line with the change.
• YAML and documentation updates (models.yaml, model_configuration.md)

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🧪 How to Test

Steps for reviewers to verify functionality:

1. Add multiple urls, auth tokens to a model in.env with | separator.
2. Run any task which uses this model.
3. Data generation should leverage all model URLs, tokens provided using the type of load_balancer set.
4. Optionally, run tests:

   make test-verbose

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Screenshots (if applicable)

N/A

Checklist

• Lint fixes and unit testing done
• End to end task testing
• Documentation updated

Notes

NO CHANGES NEEDED FROM USER END

[zephyrzilla]

Looks good to me! ✅

[amitsnow]

LGTM