fix: use locally bundled models when remote_models disabled

[sayan-oai]

Why

We see issues like #11527 when a user has remote_models disabled, as we always use the default fallback ModelInfo. This causes issues with model performance. #11690 helps by warning the user when they are using the default fallback, but we shouldn't use the fallback if we have matching ModelInfo in the locally bundled models.json.

I added ModelsManager::bundled_models as a new field, but we could also read ModelsManager::remote_models if we are ok with using cached model info when remote_models is disabled.

Tests

Updated existing test to confirm we don't use the default model info when remote_models is disabled with a slug that's in the locally bundled models.json.