Enable packed dataset for validation; add a2a_experimental argument

[michal2409]

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• [ ] Bugfix
• [ ] Documentation

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[github-actions[bot]]

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

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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

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Thank you for improving NeMo's documentation!

[github-actions[bot]]

[🤖]: Hi @michal2409 👋,

We wanted to let you know that a CICD pipeline 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