feat!: unserve long-time deprecated SubNamespace API versions

[erikgb]

These API versions were deprecated in #128, and we've had multiple releases since then.

The v1 version is causing trouble in our clusters after upgrading to Flux 2.5. We are still trying to find the root cause for this, but it seems like there are mysterious upstream code. Example: https://github.com/kubernetes/client-go/blob/master/restmapper/discovery.go#L47-L48. Since v1 SubNamespace has a controversial non-standard status, this currently gives errors like this in our clusters:

health check failed after 3m0.016039541s: timeout waiting for: [SubNamespace/stas/stas-k8s-openapi-kustomizor status: 'Unknown': looking up status.observedGeneration from resource: .status.observedGeneration accessor error: ok is of the type string, expected map[string]interface, SubNamespace/stas/stas-review status: 'Unknown': looking up status.observedGeneration from resource: .status.observedGeneration accessor error: ok is of the type string, expected map[string]interface, SubNamespace/stas/stas-spiffe-example status: 'Unknown': looking up status.observedGeneration from resource: .status.observedGeneration accessor error: ok is of the type string, expected map[string]interface]

Hopefully, making v1 unserved could fix this, and I am going to attempt this as a temporary workaround until this change is merged and released.

[erikgb]

Update: The root cause for the Flux problem is found, ref. fluxcd/kustomize-controller#1373. We have unserved old/deprecated SubNamepace APIs by patching the CRD in all our clusters as a temporary workaround. I would love to remove this patching eventually, so looking forward to a review and merge of this PR.

[ymmt2005]

LGTM. Thanks.