refresh removes everything inside proj/ folder, should only remove the $PROJECT_DESTINATION folder

When doing an autosubmit refresh on an auto-ecearth3 experiment, I lost backups which I had made of the auto-ecearth3 folder.

These .tgz files were inside the proj/ folder, and they were all removed when doing an 'autosubmit refresh'.

I think that the refresh command should only remove the $PROJECT_DESTINATION folder (e.g. auto-ecearth3), instead of the entire proj/ folder.