[User Story] - Migrate from Azure OpenAI to standard Open AI library

Description
Update to the stable Open AI java library. https://github.com/openai/openai-java

Current Behavior
It's using Azure Open AI library.

Design Considerations
Make sure to keep using managed identity support: https://github.com/openai/openai-java?tab=readme-ov-file#microsoft-azure

Start by locating the current Azure OpenAI library usage in the Java project and compare it with the stable openai-java documentation linked in the issue. Pay particular attention to the Microsoft Azure managed identity guidance. Done means the project uses the standard library, preserves managed identity support, and its existing checks still pass.

Written by the indexing model from the issue text.