Relax chat completion assertion

[markuswustenberg]

No description provided.

[Copilot]

Pull Request Overview

This PR relaxes the chat completion assertions in tests by replacing exact string matches with more flexible substring checks. The change makes tests more resilient to variations in AI model responses while still validating key content.

• Replaced exact string equality assertions with flexible substring matching
• Added helper functions to check for required content in responses
• Maintained test coverage while accommodating natural language variation in AI outputs

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