Central grafana datasources and cli fixes

[GeorgianaElena]

Fixes #1510.

This PR:

• renames the prometheus datasource of the 2i2c's Grafana to 2i2c
• creates a new deployer sub-command called grafana central-ds to manage the datasources in the central Grafana
• replaces the deployer grafana update-central-datasources command that added all clusters in the repo as datasources, in bulk to four individual commands:
  • one to add a cluster as datasource
  • one to delete a cluster from the datasources list
  • one to list all of the clusters that are not marked as datasources in the 2i2c grafana, but doesn't take any action
  • one to list all of the datasources in the central grafana that don;t have a cluster counterpart in this repo
• updates the add cluster / rm cluster with central grafana update steps.

Note, that "renaming" the prometheus data source was a bit tricky:

• this was a config that was provisioned through config, and it's marked as not editable in our support chart

  infrastructure/helm-charts/support/values.yaml

  Lines 373 to 386 in 5e12d77

  	datasources:
  	datasources.yaml:
  	apiVersion: 1
  	datasources:
  	# Automatically add the prometheus server in the same namespace as the grafana as a datasource
  	- name: prometheus
  	orgId: 1
  	type: prometheus
  	# This is the name of the kubernetes service exposed by the prometheus server
  	url: http://support-prometheus-server
  	access: proxy
  	isDefault: true
  	editable: false

  , so it had to be deleted through config
• Followed the docs at https://grafana.com/docs/grafana/latest/administration/provisioning/#data-sources to add a deleteDatasources list entry
• Then renamed the default provisioned datasource of the 2i2c cluster to be 2i2c instead of prometheus
• Then removed the deleteDatasources entry.
• Note that the datasources in deleteDatasources are first deleted, then whatever is listed under datasouces is added.

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📚 Documentation preview 📚: https://2i2c-pilot-hubs--3450.org.readthedocs.build/en/3450/

[consideRatio]

Wieee @GeorgianaElena, looks great to me!!

[GeorgianaElena]

I haven't merged this yet, because apparently apart from having 2i2c and prometheus point to the same prometheus data source there is also something called default that appears in the list of clusters in each of the Grafana panels.

However this default is not present in the list of datasource (like prometheus was), so I've been trying to figure out if I can get rid of it.

[GeorgianaElena]

Ok, finally found it 🎉 I guess looking at the same problem with fresh eyes, really does help.

Apparently having a datasource be marked as the default one, causes a placeholder called default be shown in the Grafana panels, but not in the datasources. Not having a default datasource explicitly set, solves it, and the first datasource (alphabetically) is shown as the default one in panels.

Also, I've updated the support chart to not set a default for either of the cluster's Grafana, otherwise, you are presented with two possible clusters in the panels, which is confusing.

[GeorgianaElena]

Ok, going for a merge now 🚀 Thanks for reviewing @consideRatio and @sgibson91!

[github-actions]

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Monitor the deployment of the hubs here 👉 https://github.com/2i2c-org/infrastructure/actions/runs/7044058319