fix slurmctld when not defined

Author: sjpb

templates/slurm.conf.j2

@@ -10,7 +10,9 @@ ClusterName={{ openhpc_cluster_name }}
 {% endfor %}
 
 {% set slurmctldparameters = ((openhpc_config.get('SlurmctldParameters', []) + (['enable_configless'] if openhpc_slurm_configless | bool else [])) | unique) %}
+{% if slurmctldparameters | length > 0 %}
 SlurmctldParameters={{ slurmctldparameters | join(',') }}
+{% endif %}
 
 # LOGIN-ONLY NODES
 # Define slurmd nodes not in partitions for login-only nodes in "configless" mode: