deploy-rs: disable auto-rollback by default

(as per Moira's request)

flake.nix

@@ -60,6 +60,7 @@
         hostname = "parsons";
         profiles.system = {
           user = "root";
+          autoRollback = false;
           path = deploy-rs.lib.x86_64-linux.activate.nixos
             self.nixosConfigurations.parsons;
         };