Infiniband Dashboard and better metric descriptions (#20156)

* remove acronyms

* ootb dashboard

* shrink

* Update infiniband/assets/dashboards/infiniband_overview.json

Co-authored-by: Jen Gilbert <jen.gilbert@datadoghq.com>

* slight change

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Co-authored-by: Jen Gilbert <jen.gilbert@datadoghq.com>

Author: steveny91