Found that this caused a panic after many many test runs.
It seems like we should have returned early since the pingResult is nil.
We don't want to update a lease when ping fails.
This refactors the v1 lease controller. It makes two functional differences
to the lease controller:
* It no longer ties lease updates to node pings or node status updates
* There is no fallback mechanism to status updates
This also moves vk_envtest, allowing for future brown-box testing of the
lease controller with envtest
