This commit adjusts the configuration for the `gpt-oss-120b` model to
run in plain-text mode. This is necessary because when
`reasoning_effort` is set to "medium", the reasoning tokens combined
with schema-constrained decoding can exhaust the `max_completion_tokens`
budget, leading to an empty content response.
The change restores the previous behavior where `gpt-oss-120b` was
configured without `response_format` or `top_p`, ensuring the request
body sent to Ionos remains byte-identical to the pre-multi-backend
state. This prevents regressions and maintains stability for existing
production workflows.
Brummel
0848e9581f