Upgrade Ubuntu helix queues from 22.04 VMs to containers

[richlander]

Replace bare Ubuntu 22.04 VM helix queue references with container equivalents hosted on AzureLinux 3, in preparation for Ubuntu 26.04 launch.

Changes

eng/pipelines/libraries/helix-queues-setup.yml

• Mono path and general CoreCLR set: Ubuntu.2204.Amd64.Open VM → ubuntu-26.04-helix-amd64 container
• Remove redundant 26.04 entry from extra-platforms (promoted to general set)

eng/pipelines/helix-platforms.yml

• helix_linux_x64_oldest / _internal: bare 22.04 VM → ubuntu-22.04-helix-amd64 container on AzureLinux
• helix_linux_x64_ubuntu_oldest: bare 22.04 VM → ubuntu-22.04-helix-amd64 container on AzureLinux
• helix_linux_arm64_oldest: bare 22.04 ARM VM → ubuntu-22.04-helix-arm64v8 container on AzureLinux

Not changed (intentionally)

• Android queues (Ubuntu.2204.Amd64.Android.*)
• WASM/WASI container references
• ARM container host VMs
• Build pool demands

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[Copilot]

Pull request overview

Updates Helix queue mappings for Linux “oldest” coverage by replacing Ubuntu 22.04 VM queues with container-based equivalents hosted on AzureLinux 3, and updates libraries’ default Linux x64 queue selection to use the Ubuntu 26.04 container.

Changes:

• Libraries Helix queue setup: switch Mono and general CoreCLR Linux x64 from Ubuntu 22.04 VM to Ubuntu 26.04 container; remove Ubuntu 26.04 from the extra-platforms list.
• Helix platform aliases: switch “oldest” Ubuntu 22.04 x64 (public/internal), Ubuntu 22.04 x64 (Ubuntu-oldest alias), and Ubuntu 22.04 ARM64 oldest from VM queues to AzureLinux-hosted container queues.

Reviewed changes

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

File	Description
eng/pipelines/libraries/helix-queues-setup.yml	Updates the Linux x64 default queue selection to use Ubuntu 26.04 container-based queues and adjusts extra-platforms membership.
eng/pipelines/helix-platforms.yml	Repoints “oldest” Ubuntu aliases to AzureLinux-hosted Ubuntu containers for x64 and arm64.

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[richlander]

Preparing for 26.04 LTS. Assume a month from now. We want to offer same day support.

In addition, we're going to start a push on VMs, shortly. 22.04 -> 26.04. I've been waiting for 26.04 to launch to do that. We skipped 24.04 because we were focused on Azure Linux 3 VMs at that time.

@agocke

[Copilot]

Pull request overview

Updates Helix queue configuration to replace Ubuntu 22.04 VM queue references with AzureLinux 3 hosted container queues, and to move libraries’ general/mono Linux x64 coverage to the Ubuntu 26.04 container queue in preparation for Ubuntu 26.04 rollout.

Changes:

• Switch libraries Linux x64 Mono path and general CoreCLR set from Ubuntu.2204.Amd64.Open VM to the Ubuntu 26.04 container queue hosted on AzureLinux 3.
• Update “oldest” Linux platform aliases (x64 and arm64) from Ubuntu 22.04 VM queues to Ubuntu 22.04 container queues hosted on AzureLinux 3.
• Remove redundant Ubuntu 26.04 entry from the libraries extra-platforms CoreCLR inner-loop list (now covered by the general set).

Reviewed changes

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

File	Description
eng/pipelines/libraries/helix-queues-setup.yml	Moves libraries Linux x64 queue selection to Ubuntu 26.04 container (AzureLinux 3 host) and simplifies extra-platforms list.
eng/pipelines/helix-platforms.yml	Updates “oldest” Linux x64 and arm64 variables to use Ubuntu 22.04 container queues on AzureLinux 3 instead of Ubuntu 22.04 VM queues.

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