Deleted users show as `System` in activity logs

[Boy132]

Discussed in https://github.com/pelican-dev/panel/discussions/567

^{Originally posted by JoanFont1212 August 30, 2024} Someone told me to open here a bug and i didn't see where to click, so i'm using this, i'm sorry. When a user does something in activity, delete files, etc... And you delete the user, shows the activity as the system's one with the user IP, it's a little bit confusing. Here is some proof.