Remove deprecated webhook.Defaulter/Validator interface assertions

These compile-time assertions reference webhook.Defaulter and
webhook.Validator interfaces that are removed in controller-runtime
v0.21 (OCP 4.20). The assertions are dead code — webhook registration
already uses CustomDefaulter/CustomValidator in internal/webhook/.

Removing them makes the API module forward-compatible with CR v0.21
so that consumers (like openstack-operator) can bump controller-runtime
without needing replace directives for this operator.

Signed-off-by: Martin Schuppert <mschuppert@redhat.com>

Author: stuggi

api/placement/v1beta1/api_webhook.go

@@ -30,7 +30,6 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/validation/field"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
-	"sigs.k8s.io/controller-runtime/pkg/webhook"
 	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
 )
 
@@ -51,8 +50,6 @@ func SetupPlacementAPIDefaults(defaults PlacementAPIDefaults) {
 	placementapilog.Info("PlacementAPI defaults initialized", "defaults", defaults)
 }
 
-var _ webhook.Defaulter = &PlacementAPI{}
-
 // Default implements webhook.Defaulter so a webhook will be registered for the type
 func (r *PlacementAPI) Default() {
 	placementapilog.Info("default", "name", r.Name)
@@ -75,8 +72,6 @@ func (spec *PlacementAPISpecCore) Default() {
 	// nothing here yet
 }
 
-var _ webhook.Validator = &PlacementAPI{}
-
 // ValidateCreate implements webhook.Validator so a webhook will be registered for the type
 func (r *PlacementAPI) ValidateCreate() (admission.Warnings, error) {
 	placementapilog.Info("validate create", "name", r.Name)