Sync validation metrics for ASRModel
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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.asr.models.asr_model
nemo/collections/asr/models/asr_model.py:280:0: C0301: Line too long (120/119) (line-too-long)
nemo/collections/asr/models/asr_model.py:33:0: C0115: Missing class docstring (missing-class-docstring)
************* Module nemo.core.classes.modelPT
nemo/core/classes/modelPT.py:82:0: C0301: Line too long (130/119) (line-too-long)
nemo/core/classes/modelPT.py:177:0: C0301: Line too long (121/119) (line-too-long)
nemo/core/classes/modelPT.py:184:0: C0301: Line too long (154/119) (line-too-long)
nemo/core/classes/modelPT.py:258:0: C0301: Line too long (131/119) (line-too-long)
nemo/core/classes/modelPT.py:262:0: C0301: Line too long (132/119) (line-too-long)
nemo/core/classes/modelPT.py:310:0: C0301: Line too long (160/119) (line-too-long)
nemo/core/classes/modelPT.py:390:0: C0301: Line too long (135/119) (line-too-long)
nemo/core/classes/modelPT.py:1232:0: C0301: Line too long (123/119) (line-too-long)
nemo/core/classes/modelPT.py:1469:0: C0301: Line too long (140/119) (line-too-long)
nemo/core/classes/modelPT.py:1680:0: C0301: Line too long (128/119) (line-too-long)
nemo/core/classes/modelPT.py:1699:0: C0301: Line too long (135/119) (line-too-long)
nemo/core/classes/modelPT.py:1709:0: C0301: Line too long (122/119) (line-too-long)
nemo/core/classes/modelPT.py:1835:0: C0301: Line too long (166/119) (line-too-long)
nemo/core/classes/modelPT.py:1904:0: C0301: Line too long (120/119) (line-too-long)
nemo/core/classes/modelPT.py:2058:0: C0301: Line too long (151/119) (line-too-long)
nemo/core/classes/modelPT.py:223:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:869:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:926:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:930:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:937:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:1205:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:1629:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/core/classes/modelPT.py:1747:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.73/10
```

---

Thank you for improving NeMo's documentation! [🤖]: Hi @pzelasko 👋,

We wanted to let you know that a [CICD pipeline](https://github.com/NVIDIA/NeMo/actions/runs/12263868034) 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
# What does this PR do ?

Synchronizes validation metrics across DDP ranks at the end of validation epoch. Fixes critical issue with corrupted checkpoints for multi-GPU Canary runs. Follows up on https://github.com/NVIDIA/NeMo/pull/10257

**Collection**: ASR

# Changelog 
- Multi-GPU validation metric sync for ASR models

# Usage
* You can potentially add a usage example below

```python
# Add a code snippet demonstrating how to use this 
```

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# Additional Information
* Related to # (issue)
