[Website]: Add Azure AI Foundry to the Elastic’s LLM integrations table

[alaudazzi]

Type of issue

Missing information

What documentation page is affected

https://www.elastic.co/docs/solutions/observability/applications/llm-observability

What happened?

The LLM observability page must be updated with Azure AI Foundry (doc page).

Additional info

The solution provides monitoring capability for both logs and metrics.