Adding minor fixes 
# What does this PR do ?

Add a one line overview of what this PR aims to accomplish.
it changes training config files structure to not depend on training or validation config setting
Revert back Radam instead of using pytorch implementation
unsorted lens in RADTTS Encoder

**Collection**: [Note which collection this PR will affect]

# Changelog 
- Add specific line by line info of high level changes in this PR.

# Usage
* You can potentially add a usage example below

python examples/tts/radtts.py trainer.max_epochs=400 export_dir="/dir" model.optim.lr=0.00005 model.train_ds.dataloader_params.batch_size=16 model.validation_ds.dataloader_params.batch_size=16 train_dataset="/Training_data.json" validation_datasets="Validation_data.json" pitch_mean=202.67527982176898 pitch_std=54.12737646048864  sample_rate=44100 n_window_size=2048 n_window_stride=512 highfreq=null n_fft=2048 sup_data_path="dir_for sup_data" 
# 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?
- [x ] 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)
