workflows: switch to NIXPKGS_CI specific variables

[JohnRTitor]

This will allow GitHub to run actions on those commits, specifically Eval action. Currently as these merges are commited by github-actions, Eval doesn't run on the commits.

ie, https://github.com/NixOS/nixpkgs/actions/runs/12646467735/job/35237397411?pr=371701 Processing failed due to fa2d66f commit was done by github-actions.

With this every periodic merge will be authored and commited by the nixpkgs-ci bot.

Supercedes #372041

Relevant org discussion: NixOS/org#54

PR created from a NixOS/nixpkgs branch as to make it easier to test.

[JohnRTitor]

Humm, seems like secrets are not being passed properly? https://github.com/NixOS/nixpkgs/actions/runs/12781938173/job/35630648144

[JohnRTitor]

Nice, looks like this works now! https://github.com/NixOS/nixpkgs/actions/runs/12782225893/job/35631361946

[wolfgangwalther]

LGTM.

Should we use the new token for the codeowners workflow, too? (Not sure whether it has the right permissions)

[JohnRTitor]

Should we use the new token for the codeowners workflow, too? (Not sure whether it has the right permissions)

nixpkgs-ci has the permissions I believe, but no we should not use it there. nix-owners bot only has access to requesting review, adding labels and other non-write permissions, and for security reasons, apps/workflows should only have access to the things that are deemed absolutely necessary.

[nixpkgs-ci]

Backport failed for release-24.11, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release-24.11
git worktree add -d .worktree/backport-373935-to-release-24.11 origin/release-24.11
cd .worktree/backport-373935-to-release-24.11
git switch --create backport-373935-to-release-24.11
git cherry-pick -x f6976283058deb6d6eaa30967c09b4ee471e3193 6ab6314d06d25d77c3052fb00c4bdf3d7a5027a2 38ebbf7c4fc018170ac80582f83eb076694ab010

[infinisil]

Because I was confused for a sec: This PR doesn't need to be backported because:

• The backport action is only useful on master branches (you don't need to backport PRs that are already going to the release branch)
• The periodic actions are only triggered based on the master branch

[wolfgangwalther]

Correct - I tried backporting to minimize conflicts, but then concluded the same.

[leona-ya]

As this is not backported, this action now fails with (some?) backport PRs after they're merged:

• https://github.com/NixOS/nixpkgs/actions/runs/13072265877/job/36476313398
• https://github.com/NixOS/nixpkgs/actions/runs/13050020655/job/36408033875

I'm not really sure why this step runs?

[wolfgangwalther]

As this is not backported, this action now fails with (some?) backport PRs after they're merged:

I had the same errors on every backport PR I did. After doing the backport of this in #378508, those seem to be gone now.