Use NuGetCommand to install YamlDotNet from CFS feed

[vidai-msft]

Description

This pull request refactors the installation and usage of the YamlDotNet NuGet package in the Azure pipeline and PowerShell script to improve reliability and consistency. The most important changes are grouped below:

Pipeline and package installation improvements:

• Replaced the manual PowerShell-based installation of YamlDotNet with a dedicated NuGetCommand@2 task in .azure-pipelines/sync-aliases.yml, using explicit arguments for version and output directory, and reduced retry count for failures.
• Updated environment variables passed to the PowerShell task to include YAMLDOTNETVERSION, ensuring the script receives the correct version information.

Script update for package location:

• Modified tools/Github/ParseServiceContactsList.ps1 to locate the YamlDotNet.dll based on the new package directory structure defined by the pipeline, using the agent's temp directory and explicit versioning.

Mandatory Checklist

• Please choose the target release of Azure PowerShell. (⚠️Target release is a different concept from API readiness. Please click below links for details.)

  • General release
  • Public preview
  • Private preview
  • Engineering build
  • No need for a release

• Check this box to confirm: I have read the Submitting Changes section of CONTRIBUTING.md and reviewed the following information:

• SHOULD update ChangeLog.md file(s) appropriately
  • Update src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md.
    • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header in the past tense.
  • Should not change ChangeLog.md if no new release is required, such as fixing test case only.
• SHOULD regenerate markdown help files if there is cmdlet API change. Instruction
• SHOULD have proper test coverage for changes in pull request.
• SHOULD NOT adjust version of module manually in pull request

[azure-client-tools-bot-prd]

Thanks for your contribution! The pull request validation has started. Please revisit this comment for updated status.

[Copilot]

Pull request overview

Refactors the pipeline and script to install YamlDotNet via a dedicated NuGet task and load the DLL from a deterministic packages directory under the agent temp folder.

Changes:

• Replaced PowerShell-based Install-Package with NuGetCommand@2 (custom install) in the pipeline.
• Passed YAMLDOTNETVERSION into the parsing script and updated the script to resolve YamlDotNet.dll from $(Agent.TempDirectory)/packages.

Reviewed changes

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

File	Description
tools/Github/ParseServiceContactsList.ps1	Updates DLL discovery to align with the new NuGet install output directory/versioned folder.
.azure-pipelines/sync-aliases.yml	Installs YamlDotNet using NuGetCommand@2 and exports version info for the script.