ci: Fix publishing images

[RomanNikitenko]

Generated-by: Cursor AI

What does this PR do?

This change fixes the publish job in .github/workflows/image-publish.yml failing after merges to main.
The workflow was calling docker manifest annotate for amd64-* and arm64-* source tags. Those source tags are now manifest lists, and annotate fails with:
<image>:amd64-<tag> is a manifest list.

Since platform metadata is already present from the Buildx --platform ... --push flow, explicit annotation is no longer needed. The publish step now relies on docker manifest create --amend ... --amend ... followed by docker manifest push, which is compatible with current source image format.

What issues does this PR fix?

eclipse-che/che#23745

How to test this PR?

• Merge to main and verify image-publish passes.
• Confirm publish step no longer fails with is a manifest list.
• Verify resulting tags are published:
  quay.io/che-incubator/che-code:next
  quay.io/che-incubator/che-code:insiders
  quay.io/che-incubator/che-code:insiders-<short_sha>
• Inspect manifests and confirm both platforms are present (linux/amd64, linux/arm64).

Check manifest command: podman manifest inspect quay.io/che-incubator/che-code:next

Does this PR contain changes that override default upstream Code-OSS behavior?

• the PR contains changes in the code folder (you can skip it if your changes are placed in a che extension )
• the corresponding items were added to the CHANGELOG.md file
• rules for automatic git rebase were added to the .rebase folder

[github-actions]

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[github-actions]

Pull Request images published ✨

Editor amd64: quay.io/che-incubator-pull-requests/che-code:pr-651-amd64
Editor arm64: quay.io/che-incubator-pull-requests/che-code:pr-651-arm64
Dev image: quay.io/che-incubator-pull-requests/che-code-dev:pr-651-dev-amd64