perf: remove redundant CPU→GPU→CPU transition move in learner

src/lerobot/rl/learner.py

@@ -97,7 +97,6 @@ from lerobot.utils.train_utils import (
     save_checkpoint,
     update_last_checkpoint,
 )
-from lerobot.utils.transition import move_transition_to_device
 from lerobot.utils.utils import (
     format_big_number,
     init_logging,
@@ -382,7 +381,6 @@ def add_actor_information_and_train(
             transition_queue=transition_queue,
             replay_buffer=replay_buffer,
             offline_replay_buffer=offline_replay_buffer,
-            device=device,
             dataset_repo_id=dataset_repo_id,
             shutdown_event=shutdown_event,
         )
@@ -906,7 +904,6 @@ def process_transitions(
     transition_queue: Queue,
     replay_buffer: ReplayBuffer,
     offline_replay_buffer: ReplayBuffer,
-    device: str,
     dataset_repo_id: str | None,
     shutdown_event: any,
 ):
@@ -916,7 +913,6 @@ def process_transitions(
         transition_queue: Queue for receiving transitions from the actor
         replay_buffer: Replay buffer to add transitions to
         offline_replay_buffer: Offline replay buffer to add transitions to
-        device: Device to move transitions to
         dataset_repo_id: Repository ID for dataset
         shutdown_event: Event to signal shutdown
     """
@@ -925,8 +921,6 @@ def process_transitions(
         transition_list = bytes_to_transitions(buffer=transition_list)
 
         for transition in transition_list:
-            transition = move_transition_to_device(transition=transition, device=device)
-
             # Skip transitions with NaN values
             if check_nan_in_transition(
                 observations=transition["state"],