nixos/emacs: don't restartIfChanged

Fixes https://github.com/NixOS/nixpkgs/issues/535449

This probably started happening with the rust rewrite of the switcher also
restarting user units now.

nixos/modules/services/editors/emacs.nix

@@ -80,6 +80,9 @@ in
       unitConfig = lib.optionalAttrs cfg.startWithGraphical {
         After = "graphical-session.target";
       };
+
+      # Long-lived session that ought to only be restarted manually
+      restartIfChanged = false;
     }
     // lib.optionalAttrs cfg.enable {
       wantedBy = if cfg.startWithGraphical then [ "graphical-session.target" ] else [ "default.target" ];