Set OrganizationDomain before registering the DBus service
The OrganizationDomain is used by KDBusAddons to generate the service
name used to register on the session bus so we need to set it up before
we try registering on the bus.
See: https://bugs.kde.org/show_bug.cgi?id=470246
See: https://github.com/flathub/org.kde.kleopatra/issues/34
CCBUG: 470246