chore: remove deprecated kube-rbac-proxy

[arturshadnik]

Issue

Resolves #183

Description

kube-rbac-proxy, which was previously used to secure the metrics server is being deprecated.

This PR:

• removes all use of kube-rbac-proxy and switches to the new recommended method for securing the metrics server using the built-in WithAuthenticationAndAuthorization feature from Controller-Runtime
• updates manifests and helm charts
• small kustomize update config/default/kustomization.yaml. patchesStrategicMerge is deprecated -> patches

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 49 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cmd/main.go	0.00%	49 Missing ⚠️

@@            Coverage Diff             @@
##             main     #185      +/-   ##
==========================================
- Coverage   71.05%   64.25%   -6.81%     
==========================================
  Files           9        9              
  Lines         463      512      +49     
==========================================
  Hits          329      329              
- Misses        115      164      +49     
  Partials       19       19              

Files with missing lines	Coverage Δ
cmd/main.go	0.00% <0.00%> (ø)

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[mattwelke]

Reviewed together offline.

• kube-rbac-proxy was doing auth for the metrics server.
• controller-runtime authors make auth code available and kubebuilder authors used it instead of the proxy.
• PR follows approach recommended by kubebuilder authors to add flags to main.go etc to control metrics, with metrics defaulting to enabled on port 8443 (helm chart default behavior).
• Found that the DevSpace config doesn't have the flag to start the metrics server, which means it defaults to being disabled (main.go default behavior), but that's fine because don't need metrics in DevSpace local dev.
• Found that the Service associated with reading metrics is always created, even when metrics are disabled (because we have no if in the Helm chart for it). We think this is fine for now. The extra service doesn't cause any trouble.
• Manual testing was performed to test that metrics can be retrieved at that port. But we had to add a new ClusterRoleBinding to do it. We asked for clarification about it on 🚨 Action Required: Ensure that you no longer use gcr.io/kubebuilder images kubernetes-sigs/kubebuilder#3907 (comment).

[TylerGillson]

@arturshadnik great work. Please create an epic to mandate cert-manager for validator and all plugins.