bug: cable-guy errors when using systemd-resolved.

### Bug description

I see the following in my logs:

```
Command '['sshpass', '-p', 'raspberry', 'ssh', '-o', 'StrictHostKeyChecking=no', 'pi@localhost', 'lsattr /etc/resolv.conf']' returned non-zero exit status 5.
```

It appears this is an incompatibility with how `systemd-resolved` sets up resolv.conf. In the actual OS, `/etc/resolv.conf` is a symlink:
```console
$ lsattr /etc/resolv.conf
lsattr: Operation not supported While reading flags on /etc/resolv.conf
$ cat /etc/resolv.conf
# This is /run/systemd/resolve/stub-resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
...
```

### Steps to reproduce

Not sure.

### Primary pain point(s)

_No response_

### Additional context

Possibly related to #2924

### Prerequisites

- [x] I have checked to make sure that a similar request has not already been filed or fixed.