"Multiple definitions" error message incorrect

[Joseph Borg]

When trying to connect a snap interface, I get

```
apparmor_parser output:
Multiple definitions for hat systemd_run in profile (null) exist,bailing out.
```

After some investigation of the profiles generated by snapd, the culprit seems to be a duplicated `profile systemd_run` (see https://pastebin.canonical.com/p/w6ytMRcqtR/).

I think this message should be updated to reflect this, rather than `hat` and not `profile (null)`.