Remove data processing datasources

[stephen-soltesz]

This change removes data sources from Grafana for the old data-processing cluster. The clusters and DNS names have all been removed from all projects.

Part of:

• Migrate data-processing clusters to us-central1 etl#1092

This change is 

[stephen-soltesz]

I stopped the build to prevent stepping on other changes in sandbox. I won't merge until it's been deployed and verified in sandbox.

@nkinkade IIRC, there are manual steps to delete data sources (is that correct?)

[nkinkade]

The official way to delete a provisioned datasource is by adding the datasource to a special config array that Grafana reads:

https://grafana.com/docs/grafana/latest/administration/provisioning/#data-sources

You can add the datasources to this file:

https://github.com/m-lab/prometheus-support/blob/main/config/federation/grafana/provisioning/datasources/deleted.yml

The unofficial way is outlined in the README:

https://github.com/m-lab/prometheus-support#deleting-provisioned-datasources

, when you are ready to merge.

Reviewed 3 of 3 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained

[stephen-soltesz]

Obsolete by: #1010