fix: use correct UI state for Gemma models

[iurysza]

Description

Fixes an issue where incorrect UI state was being used for Gemma models, which caused it to use the wrong turn markers to structure the conversation.

Checklist

• My code follows the code style of the project.
• I have updated the documentation (not applicable).
• I have added tests to cover my changes.

Type of Change

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

[schmidt-sebastian]

The Gemma3 task file has the prompt format encoded via it's internal configuration. Thus, the turn markers no longer need to be send from the app. Let us know if this is not working for you.