Planning: shortened the minimum follow distance from 10 to 5 (meter) to avoid...

Planning: shortened the minimum follow distance from 10 to 5 (meter) to avoid to slow response when waiting left turn.

modules/planning/common/planning_gflags.cc

@@ -187,7 +187,7 @@ DEFINE_double(destination_check_distance, 5.0,
               " it is considered to reach destination");
 DEFINE_double(nudge_distance_obstacle, 0.3,
               "minimum distance to nudge a obstacle (meters)");
-DEFINE_double(follow_min_distance, 10,
+DEFINE_double(follow_min_distance, 5.0,
               "min follow distance for vehicles/bicycles/moving objects");
 DEFINE_double(
     follow_time_buffer, 2.0,