In the resiliency gate:
* Enable the --endpoint-reconciler-type=least option for the apiserver.
* Extract etcd validation into its own stages.
* Test joining a node while one control plane node is down.
Change-Id: Id89b0816e91ab6427c5e2f4833ad4ec4e1e3d133
Depends-On: I2150d40e917567a4072a1565c1b96089f3d6fd2b