Improved message to suppress errors in _dynamo/exc.py (#97345)
If user adds simply to their code:
```python
import torch
torch._dynamo.config.suppress_errors = True
```
they will get:
```
AttributeError: module 'torch' has no attribute '_dynamo'
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97345
Approved by: https://github.com/zou3519, https://github.com/kit1980
