This is almost certainly because you don't have the systemd-timesyncd package installed, or you don't have the systemd-timesyncd service enabled.
On a very quick glance, it seems the systemd-time-wait-sync service should have been bundled into the systemd-timesyncd package when it was split from the main systemd package, however I'll have to look closer to see if there is some reason it wasn't.
This is almost certainly because you don't have the systemd-timesyncd package installed, or you don't have the systemd-timesyncd service enabled.
On a very quick glance, it seems the systemd- time-wait- sync service should have been bundled into the systemd-timesyncd package when it was split from the main systemd package, however I'll have to look closer to see if there is some reason it wasn't.