Add MLflow to tracing options

[B-Step62]

Description

MLflow support tracing integration for Strands Agents: https://mlflow.org/docs/latest/genai/tracing/integrations/listing/strands/

This PR adds it to the list of tracing options.

Type of Change

Content update/revision

Motivation and Context

MLflow is first-partiy MLOps service in SageMaker AI: https://aws.amazon.com/jp/sagemaker/ai/experiments/.

Areas Affected

Tracing

Screenshots

na

Checklist

• I have read the CONTRIBUTING document
• My changes follow the project's documentation style
• I have tested the documentation locally using mkdocs serve
• Links in the documentation are valid and working
• Images/diagrams are properly sized and formatted
• All new and existing tests pass

Additional Notes

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.