feat: add Windows Server Core LTSC 2025 images

[lemeurherve]

This change adds windowsservercore-ltsc2025 images. (Nanoserver images aren't ready yet)

In draft until #681 is merged, changes to review: https://github.com/jenkinsci/docker-ssh-agent/pull/700/changes/a5a0d2a..HEAD

Related:

• feat: add Windows Server Core LTSC 2025 images docker-agents#1315

Ref:

• Add Windows 2025 images #684

Testing done

CI

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[lemeurherve]

Same as jenkinsci/docker-agents#1315 (comment), hitting jenkinsci/docker#2382 in https://ci.jenkins.io/job/Packaging/job/docker-ssh-agent/job/PR-700/1/stages/?start-byte=222107&selected-node=158#log-158-1876, circumvented by 81e2455 (same as jenkinsci/docker#2392)