tendrl-api: fix etcd.yml hack
tendrl-api: fix etcd.yml hack

Previous code was not idempotent (multiple runs would corrupt the
etcd.yml file) and this commit fixes that problem.

usmqe/usmqe-setup,usmqe/usmqe-setup,mkudlej/usmqe-setup,mkudlej/usmqe-setup