Re-own /nix/var to 0:0, except for the per-user profiles

[grahamc]

Some users are seeing installation failures because /nix/var has corrupted permissions.

I ran:

sudo chgrp 99 /nix/var
sudo chgrp -R 99 /nix/var/log

and made sure I had a profile directory:

then got:

and confirmed my per-user directory was not changed.

Description

Checklist

• Formatted with cargo fmt
• Built with nix build
• Ran flake checks with nix flake check
• Added or updated relevant tests (leave unchecked if not applicable)
• Added or updated relevant documentation (leave unchecked if not applicable)
• Linked to related issues (leave unchecked if not applicable)

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[grahamc]

@cole-h just tested when I chown'd the directories to 99, too, and it worked as expected. It no longer fails, just fixes.

[cole-h]

The recursive chown'ing (even with the exceptions) still gives me pause but... theoretically seems OK.