Remove time.Sleep() from example service running step

This is to remove time.Sleep() call from:
https://github.com/singnet/platform-pipeline/blob/2988413cba3291c1996e22994f649f053d071fe5/publish_example_service_test.go#L341
as discussed in PR https://github.com/singnet/platform-pipeline/pull/4#discussion_r219445240