Improve structure of Hazelcast Jet implementations

The current implementations are functionally working correct, but can be improved in code quality.

For example, we can use like in the beam implementations Abstract classes for:

• HistoryServices.java
• UcXHazelcastJetFactory

Additionally, the configurations should be loaded with the ServiceConfiguration class like in the other use case implementations.

private final Configuration config = ServiceConfigurations.createWithDefaults();

Also, the HazelcastJetFactory classes are not corresponding to the factory pattern:

  /////////////
  // Layer 2 //
  /////////////

  /**
   * Build a Hazelcast JetInstance used to run a job on.
   *
   * @param logger The logger specified for this JetInstance.
   * @param bootstrapServerDefault Default bootstrap server in case no value can be derived from the
   *        environment.
   * @param hzKubernetesServiceDnsKey The kubernetes service dns key.
   * @return A Uc2HazelcastJetFactory containing a set JetInstance.
   */
  public Uc2HazelcastJetFactory buildUc2JetInstanceFromEnv(final Logger logger,