Remove default mutable arguments from AbstractEmbModel constructor
State: closed | Pull request: yes

# What does this PR do ?

This changes the constructor signature. This change is backwards compatible with existing callers. 

**Collection**: [Note which collection this PR will affect]
Diffusion for NeMo2

# Changelog 
- Remove default mutable arguments from `AbstractEmbModel` constructor

# Usage
* You can potentially add a usage example below

```python
# Add a code snippet demonstrating how to use this 
```

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**Pre checks**:
- [x] Make sure you read and followed [Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md)
- [ ] Did you write any new necessary tests?
- [ ] Did you add or update any necessary documentation?
- [ ] Does the PR affect components that are optional to install? (Ex: Numba, Pynini, Apex etc)
  - [ ] Reviewer: Does the PR have correct import guards for all optional libraries?
  
**PR Type**:
- [ ] New Feature
- [x] Bugfix
- [ ] Documentation

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## Who can review?

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# Additional Information
* Related to # (issue)


<!-- 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.diffusion.encoders.conditioner
nemo/collections/diffusion/encoders/conditioner.py:22:0: C0115: Missing class docstring (missing-class-docstring)
nemo/collections/diffusion/encoders/conditioner.py:40:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:44:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:48:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:75:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:133:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:138:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:169:0: C0115: Missing class docstring (missing-class-docstring)
nemo/collections/diffusion/encoders/conditioner.py:185:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/diffusion/encoders/conditioner.py:190:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.06/10
```

---

Thank you for improving NeMo's documentation!