Automatic merge from submit-queue (batch tested with PRs 49238, 49595, 43494, 47897, 48905)
Should not set struct pointer directly to interface which may cause potential panic
fix https://github.com/kubernetes/kubernetes/issues/43127 to avoid potential kubelet panic.
In our old implemention, interface `kubeDeps.EventClient ` (interface) will never equals to `nil` even if `eventClient `(struct pointer )was set to `nil`. `kubeDeps.ExternalKubeClient` and `kubeDeps.KubeClient` also have same potential risk.