fix(test/remove_node_test.go) fix a deadlock in the test

The go-etcd client waits for the response from the paused node. And the test waits for the reponse to continue.
Actually we do not even need that small test, since we will check the machine status afterwards.
Merge pull request #805 from xiangli-cmu/fix_test

fix(test/remove_node_test.go) fix a deadlock in the test