Update HPC Overview Dashboard for Slurm integration (DataDog#21602)

* Update HPC Overview Dashboard for Slurm integration

* Update slurm/assets/dashboards/hpc_overview_dashboard.json

Co-authored-by: Janine Chan <64388808+janine-c@users.noreply.github.com>

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Co-authored-by: Steven Yuen <steven.yuen@datadoghq.com>
Co-authored-by: Janine Chan <64388808+janine-c@users.noreply.github.com>

Author: 3 people