[BUG] Samples exported with custom models do not include the prompt template

[nmetulev]

To Reproduce
Steps to reproduce the behavior:

1. Add a custom model (such as llama)
2. Go to any genai sample and select the custom model
3. Export the project
4. Notice the generated project does not include the prompt template

Expected behavior
The exported project should work just fine with custom models, not with just curated models