[ENHANCEMENT] Elastic global prefix configuration

[Boboltus]

Describe the use case:

When deploying Camunda into an environment with an existing Elastic instance, there is no easy way of adding a prefix to all the Camunda components. We now need to update/configure all the components individually with a prefix (and the index name).

Describe the enhancement/feature:

Create a global variable in the Helm chart that can be set to configure and Elastic index prefix name and then append the component specific index name to that. For instance: global: elasticsearch: indexPrefix: demoenv01

As a result the index of Zeebe would then be: demoenv01-zeebe

Desired outcome and acceptance tests:

A global variable that can be defined to prefix all Camunda indeces. No additional change are required on component specific level (although the naming of the individual indeces should still be possible). When setting the global value, all individual component will automatically get the prefix even if there is a different index name configured on component level.

[aabouzaid]

@Boboltus Thanks for the suggestion :raised_hands: I need to check if all apps can support this.