fix(autoware_vehicle_cmd_gate): remove unused variable (#9377)

Signed-off-by: veqcc <ryuta.kambe@tier4.jp>

Author: veqcc

control/autoware_vehicle_cmd_gate/src/vehicle_cmd_gate.hpp

@@ -137,7 +137,6 @@ class VehicleCmdGate : public rclcpp::Node
   bool is_engaged_;
   bool is_system_emergency_ = false;
   bool is_external_emergency_stop_ = false;
-  bool is_filtered_marker_published_ = false;
   double current_steer_ = 0;
   GateMode current_gate_mode_;
   MrmState current_mrm_state_;