Replace networking.x-k8s.io with gateway.networking.k8s.io in hack/delete-crds.sh
Replace networking.x-k8s.io with gateway.networking.k8s.io in hack/delete-crds.sh

This patch replaces `networking.x-k8s.io` with `gateway.networking.k8s.io`
in `hack/delete-crds.sh`.

istio/gateway-api,istio/gateway-api,istio/gateway-api