Migrate deployment of monitoring stack to flux

[oliver-goetz]

/kind enhancement

What this PR does / why we need it:
This is the final step on our journey from deploying the components of the prow clusters via a custom deploy.sh to a deployment with flux.

This PR migrates the prow monitoring stack to flux. Unlike the other changes this also includes a switch from kube-prometheus to kube-prometheus-stack helm chart.
It is easier to deploy kube-prometheus-stack via flux, updated more frequently and you can configure it in a less resource consuming way.

Finally, deploy.sh and the deployer service account have been dropped too, because we don't need them anymore 😄

Which issue(s) this PR fixes:
Follow-up to #2812

Special notes for your reviewer:
/cc @timebertt

The new setup is already manually deployed to our prow clusters.

[timebertt]

Very nice, love it! Thanks for finishing the last item of this effort 🚀
I don't have much to comment :)

[timebertt]

/assign

[timebertt]

Very nice, thanks again!

Leaving a
/hold
in case you want to watch/control the rollout of this change closely. Just remove it when you're ready :)

[gardener-prow]

LGTM label has been added.

Git tree hash: 89dcc32d4be03270cb7f8c3e7bdcf46b934c3718

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: timebertt

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[oliver-goetz]

/unhold

[gardener-prow]

@oliver-goetz: Updated the plugins configmap in namespace prow at cluster gardener-prow-trusted using the following files:

• key plugins.yaml using file config/prow/plugins.yaml

In response to this:

/kind enhancement

What this PR does / why we need it:
This is the final step on our journey from deploying the components of the prow clusters via a custom deploy.sh to a deployment with flux.

This PR migrates the prow monitoring stack to flux. Unlike the other changes this also includes a switch from kube-prometheus to kube-prometheus-stack helm chart.
It is easier to deploy kube-prometheus-stack via flux, updated more frequently and you can configure it in a less resource consuming way.

Finally, deploy.sh and the deployer service account have been dropped too, because we don't need them anymore 😄

Which issue(s) this PR fixes:
Follow-up to #2812

Special notes for your reviewer:
/cc @timebertt

The new setup is already manually deployed to our prow clusters.

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