Update TSG for red team

[slister1001]

Description

Please add an informative description that covers that changes made by the pull request and link all relevant issues.

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All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

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• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull Request Overview

This PR enhances the TROUBLESHOOTING.md file for the Azure AI Evaluation SDK by expanding the "Handle RedTeam Errors" section with more detailed troubleshooting guidance and additional error scenarios.

Key changes:

• Added four new subsections covering common Red Team error scenarios (permission/authentication, agent name resolution, PyRIT errors)
• Expanded existing sections with more specific guidance and formatting improvements
• Added a Python helper function to list agents in a project
• Minor grammar and formatting corrections throughout