ignition reports warning at $.systemd.units.22.contents, line 1 col 363575: unit "container-mount-namespace.service" is enabled, but has no install section so enable does nothing

Description of problem:

In a 4.11 SNO configured via Telco ZTP process we can notice warning related to container-mount-namespace.service:

journalctl -l --system | grep 'enable does nothing'

Jul 26 12:26:54 localhost ignition[1618]: warning at $.systemd.units.22.contents, line 1 col 363575: unit "container-mount-namespace.service" is enabled, but has no install section so enable does nothing
Jul 26 12:26:54 localhost ignition[1618]: warning at $.systemd.units.23.contents: unit "container-mount-namespace.service" is enabled, but has no install section so enable does nothing

Version-Release number of selected component (if applicable):
4.11.0-rc.5

How reproducible:
100%

Steps to Reproduce:
1. Deploy and configure SNO via Telco ZTP
2. Check system journal for container-mount-namespace.service warnings

Actual results:

Jul 26 12:26:54 localhost ignition[1618]: warning at $.systemd.units.23.contents: unit "container-mount-namespace.service" is enabled, but has no install section so enable does nothing

Expected results:

No warnings re container-mount-namespace.service

Additional info:

cat /etc/systemd/system/container-mount-namespace.service

[Unit]
Description=Manages a mount namespace that both kubelet and crio can use to share their container-specific mounts

[Service]
Type=oneshot
RemainAfterExit=yes
RuntimeDirectory=container-mount-namespace
Environment=RUNTIME_DIRECTORY=%t/container-mount-namespace
Environment=BIND_POINT=%t/container-mount-namespace/mnt
ExecStartPre=bash -c "findmnt ${RUNTIME_DIRECTORY} || mount --make-unbindable --bind ${RUNTIME_DIRECTORY} ${RUNTIME_DIRECTORY}"
ExecStartPre=touch ${BIND_POINT}
ExecStart=unshare --mount=${BIND_POINT} --propagation slave mount --make-rshared /
ExecStop=umount -R ${RUNTIME_DIRECTORY}

The service seems to be running:

systemctl status container-mount-namespace.service

● container-mount-namespace.service - Manages a mount namespace that both kubelet and crio can use to share their cont>
Loaded: loaded (/etc/systemd/system/container-mount-namespace.service; static; vendor preset: disabled)
Active: active (exited) since Tue 2022-07-26 13:35:41 UTC; 21min ago
Main PID: 2443 (code=exited, status=0/SUCCESS)
Tasks: 0 (limit: 403487)
Memory: 0B
CPU: 0
CGroup: /system.slice/container-mount-namespace.service

Jul 26 13:35:41 sno.kni-qe-1.lab.eng.rdu2.redhat.com systemd[1]: Starting Manages a mount namespace that both kubelet >
Jul 26 13:35:41 sno.kni-qe-1.lab.eng.rdu2.redhat.com systemd[1]: Started Manages a mount namespace that both kubelet a