To make it easier to root-cause when /health check fails.
For example, we are using load balancer to health check
each etcd instance, and when one etcd node gets terminated,
it's hard to tell whether etcd "server" was really failing
or client (or load balancer") failed to reach the etcd cluster
which is also failure in load balancer health check.

Signed-off-by: Gyuho Lee <leegyuho@amazon.com>

…r side health check in

debug level