Revert "nixos/matrix-synapse: use python to launch synapse"

This reverts commit eb753318b3.

The homeserver script has been restored with commit
0c663e9032.

nixos/modules/services/misc/matrix-synapse.nix

@@ -651,16 +651,12 @@ in {
 
     services.postgresql.enable = mkIf usePostgresql (mkDefault true);
 
-    systemd.services.matrix-synapse =
-    let
-      python = (pkgs.python3.withPackages (ps: with ps; [ (ps.toPythonModule cfg.package) ]));
-    in
-    {
+    systemd.services.matrix-synapse = {
       description = "Synapse Matrix homeserver";
       after = [ "network.target" "postgresql.service" ];
       wantedBy = [ "multi-user.target" ];
       preStart = ''
-        ${python.interpreter} -m synapse.app.homeserver \
+        ${cfg.package}/bin/homeserver \
           --config-path ${configFile} \
           --keys-directory ${cfg.dataDir} \
           --generate-keys
@@ -691,7 +687,7 @@ in {
         WorkingDirectory = cfg.dataDir;
         PermissionsStartOnly = true;
         ExecStart = ''
-          ${python.interpreter} -m synapse.app.homeserver \
+          ${cfg.package}/bin/homeserver \
             ${ concatMapStringsSep "\n  " (x: "--config-path ${x} \\") ([ configFile ] ++ cfg.extraConfigFiles) }
             --keys-directory ${cfg.dataDir}
         '';