nixos/nextcloud: Allow disabling initial admin user creation on Nextcloud >= 32

[provokateurin]

With nextcloud/server#53212 it is not longer necessary to specify a username and password for an initial admin account during installation.

This needs a solution for #412675 in order to be able to create the adminuser through nextcloud-occ.

I will make it a draft for now due to the occ env var problem, but we can already merge it before Nextcloud 32 is released, as the logic checks for a compatible version.

The WIP commit is there to test the feature locally, because a daily build of the master branch has to be used for this unreleased feature.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• Nixpkgs 25.11 Release Notes (or backporting 24.11 and 25.05 Nixpkgs Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
• NixOS 25.11 Release Notes (or backporting 24.11 and 25.05 NixOS Release notes)
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other contributing documentation in corresponding paths.

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[provokateurin]

Rebased and included #439771 to fix the occ env vars problem.
I also found a crash with this new feature: nextcloud/photos#3148

[provokateurin]

This PR can already be reviewed and tested. Once satisfied I will remove the wip commit used for testing and we can merge it even before the release of 32.

[Ma27]

This PR can already be reviewed and tested. Once satisfied I will remove the wip commit used for testing and we can merge it even before the release of 32.

Is there a particular reason to merge this before?
For me, it'd be perfectly fine to merge this together with the introduction of v32.

[provokateurin]

Not really, just that there is no time to wait after the 32 release :)
I'm also fine just having it reviewed now, wait for the release and then rebase to have the tests validate it's working with the release as well.

[Ma27]

Looking good.

Would prefer to merge this together with the nextcloud 32 introduction.

[provokateurin]

Rebased onto #446632, so marking as draft until it is merged.

[provokateurin]

Finally ready to be merged :)

[provokateurin]

@Ma27 friendly ping :)

[Ma27]

Hm so this is a bit more complex than I like, because it's an interaction between the stateVersion and package version. I think we can just save the removal for 26.05, because nextcloud31 will be removed at that point.

Since I forgot to respond: that's fine by me.

[provokateurin]

FYI: While testing my personal infra with 25.11 I noticed this feature breaks notify_push until a user is created, but I made a fix: nextcloud/notify_push#667
Let's hope it gets merged and released soon, so this works correctly with notify_push here.

[provokateurin]

^ Fixed in v1.2.1: #458101 CC @Ma27