It doesn't make sense to always pass a AuthConfig parameter for
test cases which do not enable auth at all. So refactoring the
Client interface method so that it accepts a `ClientOption`
variadic parameter.
Signed-off-by: Benjamin Wang <wachao@vmware.com>
The alarm list is the only exception that doesn't move consistent_index
forward. The reproduction steps are as simple as,
```
etcd --snapshot-count=5 &
for i in {1..6}; do etcdctl alarm list; done
kill -9 <etcd_pid>
etcd
```
Signed-off-by: Benjamin Wang <wachao@vmware.com>
