syncserver, nixos/syncserver: remove

They have been broken for multiple releases.

nixos/modules/module-list.nix

@@ -739,7 +739,6 @@
   ./services/networking/eternal-terminal.nix
   ./services/networking/fakeroute.nix
   ./services/networking/ferm.nix
-  ./services/networking/firefox/sync-server.nix
   ./services/networking/fireqos.nix
   ./services/networking/firewall.nix
   ./services/networking/flannel.nix

nixos/modules/rename.nix

@@ -21,8 +21,7 @@ with lib;
     (mkRemovedOptionModule [ "services" "quagga" ] "the corresponding package has been removed from nixpkgs")
     (mkRemovedOptionModule [ "services" "chronos" ] "The corresponding package was removed from nixpkgs.")
     (mkRemovedOptionModule [ "services" "deepin" ] "The corresponding packages were removed from nixpkgs.")
-    (mkRemovedOptionModule [ "services" "firefox" "syncserver" "user" ] "")
-    (mkRemovedOptionModule [ "services" "firefox" "syncserver" "group" ] "")
+    (mkRemovedOptionModule [ "services" "firefox" "syncserver" ] "The corresponding package was removed from nixpkgs.")
     (mkRemovedOptionModule [ "services" "marathon" ] "The corresponding package was removed from nixpkgs.")
     (mkRemovedOptionModule [ "services" "moinmoin" ] "The corresponding package was removed from nixpkgs.")
     (mkRemovedOptionModule [ "services" "mesos" ] "The corresponding package was removed from nixpkgs.")

pkgs/top-level/all-packages.nix

@@ -21806,8 +21806,6 @@ with pkgs;
 
   systemd-journal2gelf = callPackage ../tools/system/systemd-journal2gelf { };
 
-  syncserver = callPackage ../servers/syncserver { };
-
   tailscale = callPackage ../servers/tailscale {
     buildGoModule = buildGo117Module;
   };