Zookeeper free workload generator

Closes #146 (closed).

Still missing:

• Adapt Theodolite execution Kubernetes resources and Python scripts
• Adapt Docker configurations (to fix #106 (closed))

benchmarks/workload-generator-commons/build.gradle

 dependencies {
+  implementation 'com.google.guava:guava:30.1-jre'
   implementation 'com.hazelcast:hazelcast:4.1.1'
 }
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