Simplify node lock and various small changes

Co-authored-by: Fabian Kammel <fabian@kammel.dev>
Co-authored-by: Daniel Weiße <66256922+daniel-weisse@users.noreply.github.com>

bootstrapper/internal/initserver/initserver_test.go

@@ -124,6 +124,7 @@ func TestInit(t *testing.T) {
 				fileHandler: tc.fileHandler,
 				logger:      zaptest.NewLogger(t),
 				grpcServer:  serveStopper,
+				cleaner:     &fakeCleaner{serveStopper: serveStopper},
 			}
 
 			kubeconfig, err := server.Init(context.Background(), tc.req)
@@ -253,3 +254,11 @@ func newFakeLock() *fakeLock {
 func (l *fakeLock) TryLockOnce(_, _ []byte) (bool, error) {
 	return l.state.TryLock(), nil
 }
+
+type fakeCleaner struct {
+	serveStopper
+}
+
+func (f *fakeCleaner) Clean() {
+	go f.serveStopper.GracefulStop() // this is not the correct way to do this, but it's fine for testing
+}