Fixes https://github.com/kubernetes/kubernetes/issues/61998

There are times when multiple "equal" controllerrevisions are created with
the same revision number. When this happens and this is the case for the
largest revision number, the statefulset controller will periodically
select one of the maximal controllerrevisions to be the target of the
underlying statefulset. The selection happens here: https://github.com/kubernetes/kubernetes/blob/master/pkg/controller/statefulset/stateful_set_control.go#L212.
Prior to this change this selection was random as the sort was not
stable, which caused the pods of a stable set to continually roll.