Remove grafana dependency

[BrianKopp]

What was changed

Removed Grafana dependency and related config.

Why?

Configuration & installation of monitoring tools is a cluster-level consideration, and shouldn't be specified in an application such as this.

Checklist

1. Closes [Feature Request] Remove dependency on Grafana #518

2. How was this tested:
   Diff between helm template main and this branch has no differences.

Note - if running helm from the directory or source, and if you don't run helm dependencies update, then helm will want to install grafana since it's enabled by default.

3. Any docs updates needed?

README is updated.

This will be a breaking change for folks who have grafana enabled, since it will delete their temporal-installed-grafana.

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