Remove ablation-only time_mlp_weight_decay field (dropped from open-source config class)

config.json

@@ -98,6 +98,5 @@
     "vlm_config": {},
     "action_expert_config": {},
     "num_buffer_slots": 4,
-    "time_mlp_weight_decay": 0.0,
     "cold_start_mode": "current_state"
 }