fix(integrations): store serialized `TrainingArgs` to `wandb.config` without sanitization.
Allows resuming training runs when  reusing the wandb config.

# What does this PR do?

Currently the `WandbLogger` uses the `to_sanitized_dict()` method in `TrainingArguments` to serialize the training hyperparameters. This converts nested objects and `NoneType` objects to `str` for safe serialization.  However, using the stored config when resuming a training run leads to issues while initializing the `TrainingArguments` from the `wandb.run.config`. This PR fixes this by instead using the `to_dict` method to serialize the `TrainingArguments`. The resulting dictionary can be stored in the `wandb.config` and reused to resume training runs. 


## Before submitting
- [X] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#start-contributing-pull-requests), Pull Request section?

## Who can review?


- trainer: @sgugger , @pacman100 

_The documentation is not available anymore as the PR was closed or merged._