feat: add OSSKU-based IsCgroupV2 detection and CustomizedImageTrustedLaunch distro

[aadhar-agarwal]

What this PR does:
Fixes cgroupv2 detection for BYOI scenarios and adds the CustomizedImageTrustedLaunch distro.

Changes:

• IsCgroupV2: Add explicit config.OSSKU == OSSKUAzureLinux check and switch Flatcar/ACL detection from profile.Is*() (distro-based, always false for customized images) to config.Is*() (OSSKU-based)
• Add unit tests for cgroupv2 detection
• CustomizedImageTrustedLaunch: New distro constant

Why do we need it:

• BYOI nodes using AzureLinux/Flatcar/ACL images were not getting NEEDS_CGROUPV2=true because the distro-level helpers return false for customized images

• Adding CustomizedImageTrustedLaunch as a distro avoids needing separate customized image distro constants for an OS variant to support trusted launch. (for eg. CustomizedImageACL)

  • This is a similar change to adding support for CustomizedImageLinuxGuard (in AgentBaker and aks-rp)

Which issue(s) this PR fixes:
Fixes #7999

Testing:

• [TEST All VHDs] AKS Linux VHD Build - Msft Tenant

[Copilot]

Pull request overview

This PR fixes IsCgroupV2 template detection for BYOI/customized-image scenarios by switching Flatcar/ACL checks to OSSKU-based helpers and explicitly handling AzureLinux OSSKU, and it introduces a new CustomizedImageTrustedLaunch distro to represent trusted-launch customized images without proliferating per-OS custom distro constants.

Changes:

• Update IsCgroupV2 to use config.IsFlatcar() / config.IsACL() (OSSKU-aware) and add an explicit OSSKUAzureLinux check.
• Add CustomizedImageTrustedLaunch distro and treat it as a “custom image” in bootstrapping flows.
• Add unit tests covering cgroupv2 detection for customized images and bootstrapping behavior for the new distro.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/agent/datamodel/types.go	Adds the CustomizedImageTrustedLaunch distro constant.
pkg/agent/bakerapi.go	Treats CustomizedImageTrustedLaunch like other customized images (bypasses SIG/PIR image lookup).
pkg/agent/bakerapi_test.go	Adds coverage ensuring bootstrapping doesn’t error for CustomizedImageTrustedLaunch.
pkg/agent/baker.go	Updates IsCgroupV2 to be OSSKU-aware for AzureLinux/Flatcar/ACL; includes new distro in IsCustomImage.
pkg/agent/baker_test.go	Adds tests asserting NEEDS_CGROUPV2=true for customized-image + OSSKU combinations.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated no new comments.