treewide: format all inactive Nix files

After final improvements to the official formatter implementation,
this commit now performs the first treewide reformat of Nix files using it.
This is part of the implementation of RFC 166.

Only "inactive" files are reformatted, meaning only files that
aren't being touched by any PR with activity in the past 2 months.
This is to avoid conflicts for PRs that might soon be merged.
Later we can do a full treewide reformat to get the rest,
which should not cause as many conflicts.

A CI check has already been running for some time to ensure that new and
already-formatted files are formatted, so the files being reformatted here
should also stay formatted.

This commit was automatically created and can be verified using

    nix-build a08b3a4d19.tar.gz \
      --argstr baseRev b32a094368
    result/bin/apply-formatting $NIXPKGS_PATH

nixos/tests/amazon-init-shell.nix

@@ -5,9 +5,10 @@
 # Note that other tests verify that amazon-init can treat user-data as a nixos
 # configuration expression.
 
-{ system ? builtins.currentSystem,
-  config ? {},
-  pkgs ? import ../.. { inherit system config; }
+{
+  system ? builtins.currentSystem,
+  config ? { },
+  pkgs ? import ../.. { inherit system config; },
 }:
 
 with import ../lib/testing-python.nix { inherit system pkgs; };
@@ -18,24 +19,28 @@ makeTest {
   meta = with maintainers; {
     maintainers = [ urbas ];
   };
-  nodes.machine = { lib, pkgs, ... }:
-  {
-    imports = [ ../modules/profiles/headless.nix ../modules/virtualisation/amazon-init.nix ];
-    services.openssh.enable = true;
-    system.switch.enable = true;
-    networking.hostName = "";
-    environment.etc."ec2-metadata/user-data" = {
-      text = ''
-        #!/usr/bin/bash
+  nodes.machine =
+    { lib, pkgs, ... }:
+    {
+      imports = [
+        ../modules/profiles/headless.nix
+        ../modules/virtualisation/amazon-init.nix
+      ];
+      services.openssh.enable = true;
+      system.switch.enable = true;
+      networking.hostName = "";
+      environment.etc."ec2-metadata/user-data" = {
+        text = ''
+          #!/usr/bin/bash
 
-        echo successful > /tmp/evidence
+          echo successful > /tmp/evidence
 
-        # Emulate running nixos-rebuild switch, just without any building.
-        # https://github.com/nixos/nixpkgs/blob/4c62505847d88f16df11eff3c81bf9a453a4979e/nixos/modules/virtualisation/amazon-init.nix#L55
-        /run/current-system/bin/switch-to-configuration test
-      '';
+          # Emulate running nixos-rebuild switch, just without any building.
+          # https://github.com/nixos/nixpkgs/blob/4c62505847d88f16df11eff3c81bf9a453a4979e/nixos/modules/virtualisation/amazon-init.nix#L55
+          /run/current-system/bin/switch-to-configuration test
+        '';
+      };
     };
-  };
   testScript = ''
     # To wait until amazon-init terminates its run
     unnamed.wait_for_unit("amazon-init.service")