RUBY-1333 Update change stream test for current resume behavior.
RUBY-1333 Update change stream test for current resume behavior.

In particular, "cursor not found" is a resumable error for a
getMore operation, and is otherwise not a resumable error.

mongodb/mongo-ruby-driver,saghm/mongo-ruby-driver,mongodb/mongo-ruby-driver,mongodb/mongo-ruby-driver,jonhyman/mongo-ruby-driver,saghm/mongo-ruby-driver,jonhyman/mongo-ruby-driver