let hack/update-codecgen.sh include k8s.io/metrics

hack/update-codecgen.sh

@@ -51,6 +51,9 @@ generated_files=($(
         -o -wholename '*/codecgen-*-1234.generated.go' \
       \) -prune \
     \) -name '*.generated.go' | LC_ALL=C sort -r
+
+  find ./vendor/k8s.io/metrics/ \
+    -name '*.generated.go' | LC_ALL=C sort -r
 ))
 
 # We only work for deps within this prefix.