Enable packed dataset for validation; add a2a_experimental argument
State: closed | Pull request: yes
Labels: name: Run CICD

# What does this PR do ?

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**Collection**: [Note which collection this PR will affect]

# Changelog 
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# Usage
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```python
# Add a code snippet demonstrating how to use this 
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<!-- pylint-output-strict-mode-false -->

beep boop 🤖: 🙏 The following files have warnings. In case you are familiar with these, please try helping us to improve the code base.

---

Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.collections.llm.gpt.data.packed_sequence
nemo/collections/llm/gpt/data/packed_sequence.py:94:0: C0301: Line too long (123/119) (line-too-long)
nemo/collections/llm/gpt/data/packed_sequence.py:89:0: C0115: Missing class docstring (missing-class-docstring)
************* Module nemo.collections.llm.peft.lora
nemo/collections/llm/peft/lora.py:50:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/llm/peft/lora.py:56:0: C0115: Missing class docstring (missing-class-docstring)
nemo/collections/llm/peft/lora.py:87:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/llm/peft/lora.py:99:0: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.76/10
```

---

Thank you for improving NeMo's documentation!

[🤖]: Hi @michal2409 👋,

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/11975969887) for this PR just finished successfully

So it might be time to merge this PR or get some approvals

I'm just a bot so I'll leave it you what to do next.

//cc @pablo-garay @ko3n1g