planning: stop_sign_unsupported scenario fix CREEP stage

modules/planning/conf/scenario_stop_sign_unprotected_config.pb.txt

@@ -55,8 +55,8 @@ stage_config: {
   task_type: DP_POLY_PATH_OPTIMIZER
   task_type: PATH_DECIDER
   task_type: DP_ST_SPEED_OPTIMIZER
+  task_type: SPEED_DECIDER
   task_type: PROCEED_WITH_CAUTION_SPEED
-  task_type: QP_SPLINE_ST_SPEED_OPTIMIZER
   task_config : {
     task_type : DECIDER_CREEP
     decider_creep_config : {
@@ -76,7 +76,7 @@ stage_config: {
     task_type : DP_ST_SPEED_OPTIMIZER
   }
   task_config : {
-    task_type : QP_SPLINE_ST_SPEED_OPTIMIZER
+    task_type : SPEED_DECIDER
   }
   task_config : {
     task_type : PROCEED_WITH_CAUTION_SPEED