Merge pull request #58203 from CaoShuFeng/signature

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

remove invalid and useless functions from unit test

**Release note**:
```release-note
NONE
```

staging/src/k8s.io/apiserver/pkg/admission/plugin/webhook/initializer/initializer_test.go

@@ -26,9 +26,7 @@ import (
 
 type doNothingAdmission struct{}
 
-func (doNothingAdmission) Admit(a admission.Attributes) error { return nil }
 func (doNothingAdmission) Handles(o admission.Operation) bool { return false }
-func (doNothingAdmission) Validate() error                    { return nil }
 
 type fakeServiceResolver struct{}