discoverd,router: Re-use etcd runner in discoverd tests

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
discoverd/testutil: Move up a directory level

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
discoverd/testutil: Discard stdout if we’re not logging it

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>
discoverd/testutil: Add a bit more logging

Signed-off-by: Jonathan Rudenberg <jonathan@titanous.com>