Update build image with runtime instance name for slurm controller and db

Created by: jprorama

The build-time setting of the slurm controller and db hostname cause slurm startup to fail during deploy (ops) phase. The ohpc_install_ops role updates the slurm.conf from the template to include the current names. The conditional avoids multiple writers to the file, since there is one call to the code for each client node in the cluster due to the current null resource config.