We think etcd's tendency to mistakenly mark nodes down may have
been addressed. We can't find out without checking for it.
The exact pool of methods in methodsDegraded may have bitrotted
some; for instance, it didn't have PastQueries or PartitionNodes
in it, but it looks like it reasonably should.
We rework the Replica1/Replica2 server tests to reflect the
intended semantics again.
(cherry picked from commit 164dec1703)