nixos/systemd: remove boot.initrd.systemd.extraConfig

nixos/modules/system/boot/systemd/initrd.nix

@@ -141,6 +141,12 @@ in
       It only saved ~1MiB of initramfs size, but caused a few issues
       like unloadable kernel modules.
     '')
+    (lib.mkRemovedOptionModule [
+      "boot"
+      "initrd"
+      "systemd"
+      "extraConfig"
+    ] "Use boot.initrd.systemd.settings.Manager instead.")
   ];
 
   options.boot.initrd.systemd = {
@@ -163,16 +169,6 @@ in
       '';
     };
 
-    extraConfig = mkOption {
-      default = "";
-      type = types.lines;
-      example = "DefaultLimitCORE=infinity";
-      description = ''
-        Extra config options for systemd. See {manpage}`systemd-system.conf(5)` man page
-        for available options.
-      '';
-    };
-
     settings.Manager = mkOption {
       default = { };
       defaultText = lib.literalExpression ''
@@ -488,7 +484,6 @@ in
         "/etc/systemd/system.conf".text = ''
           [Manager]
           DefaultEnvironment=PATH=/bin:/sbin
-          ${cfg.extraConfig}
           ${attrsToSection cfg.settings.Manager}
           ManagerEnvironment=${
             lib.concatStringsSep " " (