wslc container cp completely fills RAM

### Windows Version

10.0.19044.7548

### WSL Version

2.9.4.0

### Are you using WSL 1 or WSL 2?

- [x] WSL 2
- [ ] WSL 1

### Kernel Version

_No response_

### Distro Version

Debian

### Other Software

_No response_

### Repro Steps

Create a container
Copy a large directory (50 GB+) from a high-speed SSD to a slower SSD using wslc container cp:
`wslc container cp D:/Gauthier/Downloads/ComfyUI/models comfy_ui:/ComfyUI/` (in my case)

### Expected Behavior

The copy operation should complete without consuming all available RAM.
The copy operation should not create temporary files, as this wastes time and doubles the required disk space during the copy.

### Actual Behavior

Vmmem uses up to 16 GB of RAM during the copy operation and does not release the memory after the copy has finished.

### Diagnostic Logs

Before RAM usage increases :

After the temporary files have been written:

After CP is finished :