POC: Base URL in the llm/call body

**Is your feature request related to a problem?**  
We need to find a clean and efficient way to implement a specific feature. Currently, the options are limited, which complicates the development process.

**Describe the solution you'd like**  
- Take the base URL in the call body.

<details><summary>Original issue</summary>

Options
1. Take the base url in the call body

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