nixos/terminfo: Fix less in systemd stage 1

Since `less` 691, we get `terminals database is inaccessible` in
initrd. This is a problem because ordinary systemd commands like
systemctl and journalctl often try to use the pager.

Bisected to: 7bf5441da5

Fedora only adds these few terminfos to their initramfs, see dracut:
5d2bda46f4/modules.d/95terminfo/module-setup.sh (L12)

nixos/modules/config/terminfo.nix

@@ -66,6 +66,17 @@
       source = "${config.system.path}/share/terminfo";
     };
 
+    boot.initrd.systemd.contents = lib.listToAttrs (
+      lib.map
+        (ti: lib.nameValuePair "/etc/terminfo/${ti}" { source = "${pkgs.ncurses}/share/terminfo/${ti}"; })
+        [
+          "l/linux"
+          "v/vt100"
+          "v/vt102"
+          "v/vt220"
+        ]
+    );
+
     environment.profileRelativeSessionVariables = {
       TERMINFO_DIRS = [ "/share/terminfo" ];
     };

nixos/tests/all-tests.nix

@@ -1560,6 +1560,7 @@ in
   };
   systemd-initrd-simple = runTest ./systemd-initrd-simple.nix;
   systemd-initrd-swraid = runTest ./systemd-initrd-swraid.nix;
+  systemd-initrd-terminfo = runTest ./systemd-initrd-terminfo.nix;
   systemd-initrd-vconsole = runTest ./systemd-initrd-vconsole.nix;
   systemd-initrd-vlan = runTest ./systemd-initrd-vlan.nix;
   systemd-journal = runTest ./systemd-journal.nix;

nixos/tests/systemd-initrd-terminfo.nix

@@ -0,0 +1,22 @@
+{ lib, ... }:
+{
+  name = "systemd-initrd-terminfo";
+
+  meta.maintainers = [ lib.maintainers.elvishjerricco ];
+
+  nodes.machine =
+    { config, ... }:
+    {
+      boot.initrd.systemd = {
+        enable = true;
+        extraBin.script = "${config.boot.initrd.systemd.package.util-linux}/bin/script";
+      };
+      testing.initrdBackdoor = true;
+    };
+
+  testScript = ''
+    machine.wait_for_unit("initrd.target")
+    rc, out = machine.execute("echo q | script -q -e -c 'yes | less' /dev/null")
+    assert "terminals database is inaccessible" not in out
+  '';
+}