update KochFollower.get_observation() so it returns same observation structure as SO101 (#1248)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

lerobot/common/robots/koch_follower/koch_follower.py

@@ -20,7 +20,6 @@ from functools import cached_property
 from typing import Any
 
 from lerobot.common.cameras.utils import make_cameras_from_configs
-from lerobot.common.constants import OBS_STATE
 from lerobot.common.errors import DeviceAlreadyConnectedError, DeviceNotConnectedError
 from lerobot.common.motors import Motor, MotorCalibration, MotorNormMode
 from lerobot.common.motors.dynamixel import (
@@ -175,11 +174,9 @@ class KochFollower(Robot):
         if not self.is_connected:
             raise DeviceNotConnectedError(f"{self} is not connected.")
 
-        obs_dict = {}
-
         # Read arm position
         start = time.perf_counter()
-        obs_dict[OBS_STATE] = self.bus.sync_read("Present_Position")
+        obs_dict = self.bus.sync_read("Present_Position")
         obs_dict = {f"{motor}.pos": val for motor, val in obs_dict.items()}
         dt_ms = (time.perf_counter() - start) * 1e3
         logger.debug(f"{self} read state: {dt_ms:.1f}ms")