Update example usage to disable sequence_parallel
State: closed | Pull request: yes
Labels: name: NLP

# What does this PR do ?

Update example usage about sequence_parallel option to resolve an error below

```
Traceback (most recent call last):
  File "/opt/NeMo/examples/nlp/language_modeling/megatron_gpt_prune.py", line 93, in main
    model = MegatronGPTModel.restore_from(
  File "/opt/NeMo/nemo/collections/nlp/models/nlp_model.py", line 478, in restore_from
    return super().restore_from(
  File "/opt/NeMo/nemo/core/classes/modelPT.py", line 468, in restore_from
    instance = cls._save_restore_connector.restore_from(
  File "/opt/NeMo/nemo/collections/nlp/parts/nlp_overrides.py", line 1298, in restore_from
    loaded_params = super().load_config_and_state_dict(
  File "/opt/NeMo/nemo/core/connectors/save_restore_connector.py", line 182, in load_config_and_state_dict
    instance = calling_cls.from_config_dict(config=conf, trainer=trainer)
  File "/opt/NeMo/nemo/core/classes/common.py", line 530, in from_config_dict
    raise e
  File "/opt/NeMo/nemo/core/classes/common.py", line 522, in from_config_dict
    instance = cls(cfg=config, trainer=trainer)
  File "/opt/NeMo/nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py", line 331, in __init__
    super().__init__(cfg, trainer=trainer, no_lm_init=True)
  File "/opt/NeMo/nemo/collections/nlp/models/language_modeling/megatron_base_model.py", line 146, in __init__
    self.model_parallel_config: ModelParallelConfig = self.build_model_parallel_config()
  File "/opt/NeMo/nemo/collections/nlp/models/language_modeling/megatron_base_model.py", line 1194, in build_model_parallel_config
    model_parallel_config = ModelParallelConfig(**mp_config_dict)
  File "<string>", line 58, in __init__
  File "/opt/megatron-lm/megatron/core/model_parallel_config.py", line 313, in __post_init__
    raise ValueError("Can not use sequence paralllelism without tensor parallelism")
ValueError: Can not use sequence paralllelism without tensor parallelism
```

**Collection**: [Note which collection this PR will affect]

# Changelog 
- [Add sequence_parallel false arg](https://github.com/NVIDIA/NeMo/blob/0547550ad803fce1e4a019f92e9c59f4c902e7e0/examples/nlp/language_modeling/megatron_gpt_prune.py#L42)


# Usage

```
python examples/nlp/language_modeling/megatron_gpt_prune.py \
    model.restore_from_path=llama3.1-8b-instruct.nemo \
    model.tensor_model_parallel_size=1 \
    model.pipeline_model_parallel_size=8 \
    +model.sequence_parallel=false \ <-- add this line
    trainer.num_nodes=1 \
    trainer.precision=bf16 \
    trainer.devices=8 \
    prune.ffn_hidden_size=9216 \
    prune.num_attention_heads=null \
    prune.num_query_groups=null \
    prune.hidden_size=3072 \
    export.save_path=llama3.1-8b-instruct-pruned.nemo
```

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# Additional Information
* Related to # (issue)


`sequence_parallel: false` is already added to the default config now so it should not be needed anymore if you use latest container. Can you please confirm?

https://github.com/eagle705/NeMo/blob/main/examples/nlp/language_modeling/conf/megatron_gpt_prune.yaml#L26

@kevalmorabia97 
Right. It already added as you mentioned. This issue should be resolved. Thanks