Remove slurm controller from ntpclient play

[hfrSchmidt]

Otherwise the failure to enable and start the systemd unit timesyncd prevents the controller from being targeted in the subsequent plays.

[enasca]

This technically works, but it reads as if we don't want the slurm controller to be synchronised with our time server. Ideally we should communicate that we do want the slurm controller in sync, but there's nothing to do because it's containerised. I'll see if there's a convenient way for the ntpclient role to detect when it runs in a container and, if so, just do nothing.

[enasca]

Or perhaps it would be easier to simply assume that if the init system is not systemd, then the ntpclient role should just do nothing. Ansible stores this information in ansible_facts['service_mgr'].

[hfrSchmidt]

Good idea. Seems cleaner. I'll push the changes sometime today.