Added grafana dashboards

[YasminLorinKaygalak]

Description

NET-10488
Added the grafana dashboard jsons to the repo.

PR Checklist

• updated test coverage
• external facing docs updated
• appropriate backport labels added
• not a security concern

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[hashicorp-cla-app]

Thank you for your submission! We require that all contributors sign our Contributor License Agreement ("CLA") before we can accept the contribution. Read and sign the agreement

Learn more about why HashiCorp requires a CLA and what the CLA includes

_{Have you signed the CLA already but the status is still pending? Recheck it.}

[missylbytes]

So we took the readme for publishing out until we learn exactly how we need to publish these. There is a follow up story.