etcd3/store: call a generic cancelled watch test

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

Kubernetes-commit: c0fc8172559f7796560a9b80fd23df92095adb14

pkg/storage/etcd3/watcher_test.go

@@ -137,6 +137,10 @@ func TestWatchError(t *testing.T) {
 
 func TestWatchContextCancel(t *testing.T) {
 	ctx, store, _ := testSetup(t)
+	RunTestWatchContextCancel(ctx, t, store)
+}
+
+func RunTestWatchContextCancel(ctx context.Context, t *testing.T, store storage.Interface) {
 	canceledCtx, cancel := context.WithCancel(ctx)
 	cancel()
 	// When we watch with a canceled context, we should detect that it's context canceled.