Upgrade to V4 arcade publishing

[mmitche]

Upgrade to V4 Arcade Publishing

This PR migrates dotnet/machinelearning from Arcade V3 publishing to V4 publishing.

Changes

File	Change
eng/Publishing.props	<PublishingVersion>3</PublishingVersion> → <PublishingVersion>4</PublishingVersion>
build/vsts-ci.yml	Removed enablePublishUsingPipelines: true from Package job
build/vsts-ci.yml	Added enablePublishing: true and publishingVersion: 4 to Package job
build/vsts-ci.yml	Removed /p:DotNetPublishUsingPipelines=$true from _InternalBuildArgs
build/vsts-ci.yml	Removed /p:DotNetSymbolServerTokenMsdl and /p:DotNetSymbolServerTokenSymWeb from _InternalBuildArgs
build/vsts-ci.yml	Added publishingVersion: 4 to publish-build-assets.yml parameters; removed publishUsingPipelines: true
build/vsts-ci.yml	Changed publishingInfraVersion: 3 → publishingInfraVersion: 4 on post-build template

Validation tracking

• Official validation build: https://dev.azure.com/dnceng/internal/_build/results?buildId=2959647 (succeeded)
• Promotion build: Build 311816 promoted to General Testing Internal (--skip-assets-publishing; succeeded)
• Asset comparison: baseline BAR 309458 (build 20260408.1) vs BAR 311816 (build 20260424.2) — 81 assets each, names match (only version-embedded path differences)
• Tracker: Tracking: onboard .NET Eng - Latest subscription targets to Arcade V4 publishing arcade#16697

[Copilot]

Pull request overview

Migrates the ML.NET repository’s official build pipeline from Arcade V3 publishing to Arcade V4 publishing, aligning both MSBuild publishing properties and Azure DevOps template parameters with the newer publishing infrastructure.

Changes:

• Bumped Arcade publishing version from 3 → 4 via eng/Publishing.props.
• Updated the official Azure DevOps pipeline to opt into V4 publishing (enablePublishing: true, publishingVersion: 4) and removed V3-era publishing flags/args.
• Switched post-build promotion to publishing infra v4 (publishingInfraVersion: 4) and updated publish-build-assets parameters accordingly.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
eng/Publishing.props	Updates the repo-wide publishing version property to 4.
build/vsts-ci.yml	Updates official build/publishing configuration to Arcade publishing V4 and removes V3-specific flags/arguments.