Bug#1065466: fwupd-refresh: Can't start as the user is not created during package installation

[Arnaud Rebillout <arnaudr@kali.org>]

Package: fwupd
Version: 1.9.13-1
Severity: important
Tags: patch
User: devel@kali.org
Usertags: origin-kali

Dear Maintainer,

Steps to reproduce: on a clean Debian sid system, install fwupd, then
try to start the fwupd-refresh service. It fails with:

```
systemd[1]: Starting fwupd-refresh.service - Refresh fwupd metadata and update motd...
(fwupdmgr)[3669]: fwupd-refresh.service: Failed to determine user credentials: No such process
systemd[1]: fwupd-refresh.service: Main process exited, code=exited, status=217/USER
systemd[1]: fwupd-refresh.service: Failed with result 'exit-code'.
systemd[1]: Failed to start fwupd-refresh.service - Refresh fwupd metadata and update motd.
```

The issue is that the fwupd-refresh user doesn't exist,  as can be seen
with `grep fwupd /etc/passwd`.

The bug was introduced with commit 6e3af79c on 2023-10-06, where the
adduser command in the fwupd.postinst was dropped, and instead a file
/usr/lib/sysusers.d/fwupd.conf was introduced.

However it's not enough to install a drop-in file in sysusers.d/, one
must also call systemd-sysusers in the postinst script, which is
achieved thanks to dh_installsysusers.

Please find the fix at:

https://salsa.debian.org/efi-team/fwupd/-/merge_requests/14

Thanks,

Arnaud