Fixes training parameter for Shadow Hand (#2421)

# Description

Fixes incorrect batch size for
Isaac-Repose-Cube-Shadow-OpenAI-FF-Direct-v0

## Type of change

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- Bug fix (non-breaking change which fixes an issue)


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Author: kellyguo11

source/isaaclab_tasks/isaaclab_tasks/direct/shadow_hand/agents/rl_games_ppo_ff_cfg.yaml

@@ -79,7 +79,7 @@ params:
     bounds_loss_coef: 0.0001
 
     central_value_config:
-      minibatch_size: 32864
+      minibatch_size: 32768
       mini_epochs: 4
       learning_rate: 5e-4
       lr_schedule: adaptive