Remove Bitnami Helm Chart for thanos

[simcod]

We want to remove the dependency on the bitnami helm chart.

releases/release.yaml

Lines 343 to 345 in 6e696f9

	thanos:
	repository: https://charts.bitnami.com/bitnami
	version: 12.8.3

An alternative solution would be Grafana Mimir. It offers a helm chart.
However, this would introduce an architectural shift and a migration from Thanos to Mimir would be necessary.

Alternatively, we could remove the bitnami helm chart and create our own Thanos deployment via metal-roles. Necessary manifests can be found in kube-thanos.

[ostempel]

I ran into the same problem while fixing the monitoring. @vknabel pointed out that the kube-prometheus-stack already provides thanos. Maybe we can use the "built-in" option.

https://github.com/prometheus-community/helm-charts/blob/6a7f0044b6dcac00f601327d9c5730559fb4eb05/charts/kube-prometheus-stack/values.yaml#L3332-L3338

[iljarotar]

@ostempel could you take a look at this?

[ostempel]

I investigated a little bit on this issue.

It seems like the kube-prometheus-stack hasn't full compatibility with the bitnami/thanos helm chart. But I think we still can use the bitnami/thanos helm-chart since we are using images from quay.io/thanos:

releases/release.yaml

Lines 218 to 221 in a5e4e12

	thanos:
	name: quay.io/thanos/thanos
	repository: https://github.com/thanos-io/thanos
	tag: v0.33.0

So we are not affected by bitnami changes of image distribution.

@simcod @vknabel What do you think about this?

[simcod]

Thanks for looking into this. I agree. Let's keep using the helm chart and just replace the image.