shares-admin can't install services - failed to install package: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.PackageKit was not provided by any .service files

[N0rbert]

Steps to reproduce:

1. Have Ubuntu MATE 20.04 LTS installed
2. Launch shares-admin
3. Confirm installation of sharing services by clicking "Install services" in the opened window

Expected results:

• services are installed

Actual results:

• services are not installed, terminal shows the error:

** (shares-admin:9029): WARNING **: 12:11:42.050: failed to install package: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.freedesktop.PackageKit was not provided by any .service files

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-system-tools 3.0.0-9ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.4
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Mon Jul 27 12:06:27 2020
InstallationDate: Installed on 2020-07-08 (18 days ago)
InstallationMedia: Ubuntu-MATE 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: gnome-system-tools
UpgradeStatus: No upgrade log present (probably fresh install)

Downstream bug-report - https://bugs.launchpad.net/ubuntu/+source/gnome-system-tools/+bug/1889057

[N0rbert]

Still happens on Ubuntu MATE 22.04 LTS.