nixos/systemd: don't require network-online.target for multi-user.taget v2 (#365809)

nixos/doc/manual/release-notes/rl-2505.section.md

@@ -126,6 +126,16 @@
 
 - `gkraken` software and `hardware.gkraken.enable` option have been removed, use `coolercontrol` via `programs.coolercontrol.enable` option instead.
 
+- To avoid delaying user logins unnecessarily the `multi-user.target` is no longer ordered after `network-online.target`.
+  System services requiring a connection to start correctly must explicitly state so, i.e.
+  ```nix
+  systemd.services.<name> = {
+    wants = [ "network-online.target" ];
+    after = [ "network-online.target" ];
+  };
+  ```
+  This changed follows a deprecation period of one year started in NixOS 24.05 (see [PR #283818](https://github.com/NixOS/nixpkgs/pull/283818)).
+
 - `nodePackages.ganache` has been removed, as the package has been deprecated by upstream.
 
 - `virtualisation.azure.agent` option provided by `azure-agent.nix` is replaced by `services.waagent`, and will be removed in a future release.

nixos/modules/system/boot/systemd.nix

@@ -675,7 +675,6 @@ in
     systemd.services.systemd-udev-settle.restartIfChanged = false; # Causes long delays in nixos-rebuild
     systemd.targets.local-fs.unitConfig.X-StopOnReconfiguration = true;
     systemd.targets.remote-fs.unitConfig.X-StopOnReconfiguration = true;
-    systemd.targets.network-online.wantedBy = [ "multi-user.target" ];
     systemd.services.systemd-importd.environment = proxy_env;
     systemd.services.systemd-pstore.wantedBy = [ "sysinit.target" ]; # see #81138