Notebook Bug Fixes for r1.8.0
Signed-off-by: Virginia Adams <vadams@nvidia.com>

Notebook bug fixes for nv-bugs: 

https://nvbugswb.nvidia.com/NVBugs5/redir.aspx?url=/3596793 [ML-NeMo][A30] Text_Classification_Sentiment_Analysis.ipynb failed with ConfigAttributeError: Key 'model' is not in struct

https://nvbugswb.nvidia.com/NVBugs5/redir.aspx?url=/3596634 [ML-NeMo][A30] Joint_Intent_and_Slot_Classification.ipynb failed with ConfigAttributeError: Key 'model' is not in struct

https://nvbugswb.nvidia.com/NVBugs5/redir.aspx?url=/3596616 [ML-NeMo][A30] Entity_Linking_Medical.ipynb failed with MisconfigurationException: `Trainer(strategy='ddp')`

**Collection**: N/A

# Changelog 
Changed `nlp_model.py` and 3 tutorial notebooks

# Usage
* You can potentially add a usage example below

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

# Before your PR is "Ready for review"
**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

If you haven't finished some of the above items you can still open "Draft" PR.


## Who can review?

Anyone in the community is free to review the PR once the checks have passed. 
[Contributor guidelines](https://github.com/NVIDIA/NeMo/blob/main/CONTRIBUTING.md) contains specific people who can review PRs to various areas.

# Additional Information
* Related to # (issue)
