Remove hard coded strings. Migrate to use IConfiguration

[conniey]

What does this PR do?

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Related issues from migration

• dotnet format resulting in IL2026 and IL3050 despite using source generation for configuration. (See: https://github.com/dotnet/sdk/issues/45054)
• https://github.com/dotnet/runtime/issues/121718
• https://github.com/mysql-net/MySqlConnector/issues/1607

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GitHub issue number?

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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
  • [ ] Updated servers/Azure.Mcp.Server/CHANGELOG.md and/or servers/Fabric.Mcp.Server/CHANGELOG.md for product changes (features, bug fixes, UI/UX, updated dependencies)
• [ ] 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 using script at eng/scripts/Process-PackageReadMe.ps1. See Package README
  • [ ] Updated command list in /servers/Azure.Mcp.Server/docs/azmcp-commands.md and/or /docs/fabric-commands.md
  • [ ] Run .\eng\scripts\Update-AzCommandsMetadata.ps1 to update tool metadata in azmcp-commands.md (required for CI)
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• [ ] Extra steps for Azure MCP Server tool changes:
  • [ ] Updated test prompts in /servers/Azure.Mcp.Server/docs/e2eTestPrompts.md
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    • [ ] Manual tests run: added comment /azp run mcp - pullrequest - live to run Live Test Pipeline