Drop the manual KongCertificate/KongSNI workaround

Turned out unnecessary: the real blocker was the missing
konghq.com/secret=true label on the Vault-sourced Secret, not a gap
in the Gateway API TLS translation itself. Once that label was added
(k8s-platform), the operator's own auto-generated KongCertificate/SNI
started working and this manual one just collided with it.

kong/rest/certificate.yaml

@@ -1,23 +0,0 @@
-apiVersion: configuration.konghq.com/v1alpha1
-kind: KongCertificate
-metadata:
-  name: ${NAME}
-  namespace: ${NAMESPACE}
-spec:
-  controlPlaneRef:
-    type: konnectNamespacedRef
-    konnectNamespacedRef:
-      name: ${CONTROL_PLANE_REF_NAME}
-  type: secretRef
-  secretRef:
-    name: ${NAME}-tls
----
-apiVersion: configuration.konghq.com/v1alpha1
-kind: KongSNI
-metadata:
-  name: ${NAME}
-  namespace: ${NAMESPACE}
-spec:
-  name: ${REST_HOSTNAME}
-  certificateRef:
-    name: ${NAME}