landscape-config does not start landscape-client service

This bug was discovered during verification of the fix for LP: #2027613

[ Impact ]

The new ExecCondition in landscape-client.service provided in the patch for LP: #2027613 prevents the final steps of the landscape-config Client configuration wizard from starting the landscape-client service. landscape-config attempts to start the service via systemd to facilitate registration with Landscape Server. However, with the patch, the service cannot start prior to registration.

As a result, landscape-config cannot successful complete registration with Landscape Server.

This affects the versions in focal-proposed and jammy-proposed related to LP: #2006402, but not versions in lunar or mantic, as this bug was introduced in the proposed patch for that SRU.

[ Test Plan ]

install landscape-client, execute `sudo landscape-config` and complete the wizard.
expected behaviour: registration is successful and the landscape-client service is running. landscape-client behaves normally for a number of message exchanges and dispatched Landscape actions, such as reboot and package upgrade.

[ Where problems could occur ]

As this is a change to the landscape-config behaviour, problems would likely present as the service not running, the service running when it should not be, or in the registration or setup/config behaviour.