eks-prow-build-cluster: Replace FluxCD with ArgoCD

[xmudrii]

It has been discussed to replace FluxCD that we use for eks-prow-build-cluster with ArgoCD. ArgoCD offers many more features that can help us to easier manage all our clusters (e.g. UI, terminal/console, easier to debug issues...).

### Tasks
- [ ] Investigate what does it take to replace FluxCD with ArgoCD and come up with a proposal
- [ ] Investigate multi-cluster setup for ArgoCD (e.g. so that we can manage both GKE and EKS clusters with it)
- [ ] Set up a new cluster to host ArgoCD and the monitoring stack
- [ ] Deploy ArgoCD
- [ ] Migrate eks-prow-build-cluster from FluxCD to ArgoCD

/assign @xmudrii @koksay
/sig k8s-infra
/area infra infra/aws
/milestone v1.30
/priority important-soon

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/lifecycle stale

[xmudrii]

/remove-lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Mark this issue as fresh with /remove-lifecycle stale
• Close this issue with /close
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/lifecycle stale