chore(ground_segmentation): add default params (#831)

Signed-off-by: badai-nguyen <dai.nguyen@tier4.jp>
Co-authored-by: kminoda <44218668+kminoda@users.noreply.github.com>

autoware_launch/config/perception/obstacle_segmentation/ground_segmentation/ground_segmentation.param.yaml

@@ -30,3 +30,6 @@
         detection_range_z_max: 2.5
         elevation_grid_mode: true
         use_recheck_ground_cluster: true
+        low_priority_region_x: -20.0
+        center_pcl_shift: 0.0
+        radial_divider_angle_deg: 1.0