Checkpoints Saving with different permissions to account defaults

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### Bug description

When working on a managed cluster all our files save with "-rw-r--r--" permissions. However the checkpoint files from lightning are being saved with "-rw-------" permissions. We've gone round in circles trying to debug this and do not understand. Is there anything in the lightning code base that is causing this/is it configurable?

### Environment

Current environment

```
#- PyTorch Lightning Version (e.g., 2.4.0): 2.4.0
#- PyTorch Version (e.g., 2.4): 2.4
#- Python version (e.g., 3.12): 3.12
#- OS (e.g., Linux): Ubuntu 22
#- CUDA/cuDNN version: 12.5
#- GPU models and configuration: `8xH100`
#- How you installed Lightning(`conda`, `pip`, source): `conda`
```

Reproduce checkpoint saving with Lightning 2.4.0 in the reported Ubuntu 22, Python 3.12, PyTorch 2.4 environment and compare its permissions with other saved files. Trace the checkpoint-saving entry point to determine whether Lightning sets the restrictive permissions, then identify whether the behavior is configurable and document the observed result.

Written by the indexing model from the issue text.