Remove deprecation in ObservationContext for models

[ThomasVitale]

In 1.0.0-M6, the ".requestOptions()" method for ModelObservationContext instances has been deprecated and marked for removal. This issue is to track the changes needed to use the new strategy and remove the deprecated logic.

• Anthropic
• Azure OpenAI
• Bedrock Converse
• Mistral AI => mistral: Adopt new strategy for ObservationContext #2519
• OCI GenAi
• Ollama => ollama: Adopt new strategy for ObservationContext #2520
• OpenAI => openai: Adopt new strategy for ObservationContext #2521
• Transformers
• VertexAI Embedding
• VertexAI Gemini
• Minimax
• ZhiPu