chore: simplify and standardize cloud-final.service (canonical#5830)

- There is no harm in ordering after a service which doesn't exist.
- Cloud-init's final stage should consistently be ordered with respect to
  multi-user.target on all distros.

systemd/cloud-final.service.tmpl

@@ -3,10 +3,8 @@
 # https://docs.cloud-init.io/en/latest/explanation/boot.html
 Description=Cloud-init: Final Stage
 After=network-online.target time-sync.target cloud-config.service rc-local.service
-{% if variant in ["ubuntu", "unknown", "debian"] %}
 After=multi-user.target
 Before=apt-daily.service
-{% endif %}
 Wants=network-online.target cloud-config.service
 ConditionPathExists=!/etc/cloud/cloud-init.disabled
 ConditionKernelCommandLine=!cloud-init=disabled