Remove duplicate check for existing finalizer

[al3xandru]

(Minor) Method AddFinalizers is doing a check if the finalizer is already present before delegating to controllerutil.AddFinalizer. The implementation of controllerutil.AddFinalizer is doing that check too already: https://github.com/kubernetes-sigs/controller-runtime/blob/7ba3e559790c5e3543002a0d9670b4cef3ccf743/pkg/controller/controllerutil/controllerutil.go#L351

[jayasheelankumar]

@al3xandru, Thanks for pointing. We will update the logic in our next release.