Use '<|finetune_right_pad|>' as padding token for LLama4 (#2988) [skip ci]

examples/llama-4/scout-vision-qlora-fsdp2-flex.yaml

@@ -85,7 +85,7 @@ fsdp_config:
   fsdp_reshard_after_forward: true
   fsdp_activation_checkpointing: true
 special_tokens:
-  pad_token: <|finetune_right_pad_id|>
+  pad_token: <|finetune_right_pad|>
   eos_token: <|eot|>
 
 # save_first_step: true  # uncomment this to validate checkpoint saving works with your config