[WIP] Remove stale .NET 11 test data entries for Alpine 3.22 and Windows LTSC2022

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

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<issue_title>Remove stale .NET 11 test data entries for Alpine 3.22 and Windows LTSC2022</issue_title>
<issue_description>tests/Microsoft.DotNet.Docker.Tests/TestData.cs on the nightly branch contains 13 .NET 11 (V11_0) test data entries that reference OS versions with no corresponding Dockerfiles:

• 11 Alpine 3.22 entries — amd64, arm64, arm (regular, composite SDK, and AOT variants)
• 2 Windows LTSC2022 entries — NanoServer and ServerCore for amd64

There are no .NET 11 Dockerfiles for Alpine 3.22 or Windows LTSC2022 on the nightly branch. The .NET 11 Dockerfiles only target Alpine 3.23, Azure Linux 3.0, Ubuntu Resolute, and Windows LTSC2025.

These entries were likely left over from when .NET 11 images were initially added (#6872) — either the entries anticipated Dockerfiles that were later dropped, or the Dockerfiles were removed without a corresponding test data cleanup.

Why TestDataTests doesn't catch this

TestDataTests.VerifyTestData only checks one direction: it verifies that every Dockerfile in the manifest has a corresponding entry in test data. It does not verify the reverse — that every test data entry maps to an actual Dockerfile. Stale test data entries are silently ignored.

Expected fix: Remove the 13 stale V11_0 entries for Alpine322, NanoServerLtsc2022, and ServerCoreLtsc2022 from TestData.cs.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Remove stale .NET 11 test data entries for Alpine 3.22 and Windows LTSC2022 #7034

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