AzureAISearchTool service availability: GA or Public Preview

Azure AISearchTool available in Agent Service v2 ([link](https://learn.microsoft.com/en-us/azure/foundry/agents/how-to/tools/ai-search?tabs=keys%2Cazurecli&pivots=python)) internally uses Agentic retrieval feature ([link](https://learn.microsoft.com/en-us/azure/search/agentic-retrieval-overview?tabs=quickstarts)) of AI Search which is still in Public Preview.

However, Python, Java Script and REST APIs for AISearchTool available in Agent Service v2 ([link](https://learn.microsoft.com/en-us/azure/foundry/agents/how-to/tools/ai-search?tabs=keys%2Cazurecli&pivots=python)) are marked as GA, although the backend service (Agentic retrieval feature) is not GA yet and and hence not ready for production.

Considering, AISearchTool is being considered as an alternative of deprecated Azure OpenAI On-Your-Data service, it would be great if documentation is updated with the availability status from API as well as service availability perspective.

cc: cc: @xiangyan99, @lindazqli, @leestott, @guygregory