docs: point llamaindex model lists to uipath list-models

[radu-mocanu]

Summary

• replace the outdated, hardcoded model lists in the llamaindex LLMs and embeddings docs with an "Available models" section that runs uipath list-models (shows the models actually available on the user's tenant) and notes they are subject to AI Trust Layer policies
• align the intro and the model table format with the langchain chat models docs

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

Updates the uipath-llamaindex “LLMs and Embeddings” documentation to avoid hardcoded provider model lists by pointing users to uipath list-models, which reflects the models enabled on their tenant (and governed by AI Trust Layer policies).

Changes:

• Adds an “Available models” section that demonstrates uipath list-models output and shows how to pass model IDs into provider-specific classes.
• Replaces hardcoded OpenAI / Bedrock / Vertex model lists with references to the uipath list-models output columns.
• Aligns wording/structure around model selection across the provider sections.

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