Validating webhook fails to deploy on k8s v1.22+

[michaelbeaumont]

What happened:

Gateway API resources fail to validate after installing the webhook on k8s v1.22:

kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/master/deploy/certificate_config.yaml
kubectl apply -f https://raw.githubusercontent.com/kubernetes-sigs/gateway-api/master/deploy/admission_webhook.yaml

Error from server (InternalError): error when creating "gatewayapi.yaml": Internal error occurred: failed calling webhook "validate.gateway.networking.k8s.io": Post "https://gateway-api-admission-server.gateway-api.svc:443/validate?timeout=10s": x509: certificate signed by unknown authority

because the gateway-api-admission-patch Job fails to generate a certificate with the error message:

{"err":"the server could not find the requested resource","level":"fatal","msg":"failed getting validating webhook","source":"k8s/k8s.go:48","time":"2021-08-26T10:16:43Z"}

What you expected to happen:

The webhook certificate to be generated and resources to be validated.

How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:
This is a known issue with jet/kube-webhook-certgen, because of which it has been moved into kubernetes/ingress-nginx and is released at k8s.gcr.io/ingress-nginx.

/area webhook