Set AppConfigurationAudience based on Cloud configuration when creating App Configuration SDK clients

[alzimmermsft]

What does this PR do?

Fixes authentication issues with App Configuration tools where they weren't setting AppConfigurationAudience based on the cloud configuration of Azure MCP, resulting in a mismatch audience issue.

Now all App Configuration SDKs have AppConfigurationAudience configured based on which cloud is being interacted with.

GitHub issue number?

[Link to the GitHub issue this PR addresses]

Pre-merge Checklist

• Required for All PRs
  • Read contribution guidelines
  • PR title clearly describes the change
  • Commit history is clean with descriptive messages (cleanup guide)
  • Added comprehensive tests for new/modified functionality
  • Created a changelog entry if the change falls among the following: new feature, bug fix, UI/UX update, breaking change, or updated dependencies. Follow the changelog entry guide
• For MCP tool changes:
  • One tool per PR: This PR adds or modifies only one MCP tool for faster review cycles
  • Updated servers/Azure.Mcp.Server/README.md and/or servers/Fabric.Mcp.Server/README.md documentation
  • Validate README.md changes running the script ./eng/scripts/Process-PackageReadMe.ps1. See Package README
  • For new or modified tool descriptions, ran ToolDescriptionEvaluator and obtained a score of 0.4 or more and a top 3 ranking for all related test prompts
  • For tools with new names, including new tools or renamed tools, update consolidated-tools.json
  • For renamed tools, follow the Tool Rename Checklist and tag the PR with the breaking-change label
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• Extra steps for Azure MCP Server tool changes:
  • Updated command list in servers/Azure.Mcp.Server/docs/azmcp-commands.md
  • Ran ./eng/scripts/Update-AzCommandsMetadata.ps1 to update tool metadata in azmcp-commands.md (required for CI)
  • Updated test prompts in servers/Azure.Mcp.Server/docs/e2eTestPrompts.md
  • 👉 For Community (non-Microsoft team member) PRs:
    • Security review: Reviewed code for security vulnerabilities, malicious code, or suspicious activities before running tests (crypto mining, spam, data exfiltration, etc.)
    • Manual tests run: added comment /azp run mcp - pullrequest - live to run Live Test Pipeline

[Copilot]

Pull request overview

This PR fixes Azure App Configuration authentication issues in sovereign clouds by configuring ConfigurationClientOptions.Audience based on the active Azure cloud configuration when creating App Configuration SDK clients.

Changes:

• Set ConfigurationClientOptions.Audience according to TenantService.CloudConfiguration.CloudType when creating ConfigurationClient.
• Pass the tenant argument through to the App Configuration store resource-graph lookup.
• Add an Azure MCP Server changelog entry for the bug fix.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
tools/Azure.Mcp.Tools.AppConfig/src/Services/AppConfigService.cs	Configures App Configuration SDK client audience based on cloud; threads tenant through store lookup; adds helper for audience mapping.
servers/Azure.Mcp.Server/changelog-entries/1774886640626.yaml	Documents the bug fix in the server changelog entries.