Use Zookeeper-less workload generator

With #146 (closed) being implemented, we don't need ZooKeeper anymore for the workload generation. For the Kotlin implementation, there shouldn't be much changes, but no ZooKeeper client/reset tool will be required anymore. Also passing the total number of instances as an environment variable is not required anymore. All required environment variables are already set in the Kubernetes YAML files in the master repository.