etcd3/store: update cancelled watch test to be generic
etcd3/store: update cancelled watch test to be generic

There's no reason to create the watch using the underlying watcher.

Signed-off-by: Steve Kuznetsov <skuznets@redhat.com>

Kubernetes-commit: 774870611c1d2b405d67eb73ade628ced5e0e994

kubernetes/apiserver,kubernetes/apiserver