[Builder] Make it more clear in the LLM Block which provider each model belongs to

Currently, in the LLM block we don't specify the provider, just a list of models. It's causing confusion when some providers have the same model options.

For example Llama models are provided by both Groq and Ollama and it's not clear to our community

Start in the Builder's LLM block and inspect how its model list is presented. Trace how provider and model information is supplied, then verify that each model is visibly associated with its provider, including duplicate model names such as Llama from Groq and Ollama.

Written by the indexing model from the issue text.