Checkpoint adding "version_" at the start of the logger name

[Etienne-Meunier]

To reproduce :

logger = pl.loggers.TensorBoardLogger(
                save_dir='.',
                version='my_name'
                name='lightning_logs'
            )

trainer = pl.Trainer(logger=logger, log_gpu_memory='all', max_epochs=10)

Giving as a result:

• /lightning_logs/my_name: Where is saved the logs
• /lightning_logs/version_my_name : Where is saved the checkpoints

Possible Explanation:
It seems like the checkpoint saving add "version_" to the start of the name even if the name have been given as a parameter :

https://github.com/PyTorchLightning/pytorch-lightning/blob/3e8f2d99a9951bfb5fc67a98614128317913be1d/pytorch_lightning/trainer/callback_config.py#L52-L57

Even if in the Tensorboard Logger if the name is provided there is no "version_" prefix :

https://github.com/PyTorchLightning/pytorch-lightning/blob/8b82ce09039e75f3fcb77a987c964249e38def3b/pytorch_lightning/loggers/tensorboard.py#L81

[github-actions]

Hi! thanks for your contribution!, great first issue!