nixos/jenkins: Apply hardening options (#435751)

        StateDirectory = lib.mkIf (lib.hasPrefix "/var/lib/jenkins" cfg.home) "jenkins";

        # For (possible) socket use

        RuntimeDirectory = "jenkins";

        AmbientCapabilities = "";

        CapabilityBoundingSet = "";

        LockPersonality = true;

        # MemoryDenyWriteExecute = false;   Breaks execution;

        NoNewPrivileges = true;

        PrivateDevices = true;

        PrivateMounts = true;

        PrivateTmp = true;

        ProtectClock = true;

        ProtectControlGroups = true;

        ProtectHome = true;

        ProtectHostname = true;

        ProtectKernelLogs = true;

        ProtectKernelModules = true;

        ProtectKernelTunables = true;

        ProtectSystem = "full";

        RemoveIPC = true;

        RestrictAddressFamilies = [

          "AF_UNIX"

          "AF_INET"

          "AF_INET6"

        ];

        RestrictNamespaces = true;

        RestrictRealtime = true;

        RestrictSUIDSGID = true;

        SystemCallArchitectures = "native";

        UMask = 27;

      };

    };

  };