Removed unnecessary header for custom llm

[nicola-corbellini]

Description

This PR removes unnecessary headers used for posting to the custom llm API and removed the AI prefix in the Cat's answer.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas