[ISSUE] Propose clearer descriptions for retention Helm chart values

[houssain-barouni]

Describe the issue:

The descriptions for both orchestration.retention.enabled and orchestration.history.retention.enabled are currently the same, which is misleading.
Both settings control ILM (Index Lifecycle Management) policies for retention, but they target different kinds of indices and function differently.

Desired Clarifications:

orchestration.retention: Should specifically state that this` configuration handles retention for Zeebe record indices, i.e., those created by the legacy Elasticsearch or Opensearch exporters.
The setting configures the creation and application of ILM policies for these exporter indices, allowing customization of their retention period.
Suggested Description: Enables ILM Policy creation and application for Zeebe record (legacy Elasticsearch/Opensearch exporter) indices; controls their retention.

orchestration.history.retention.enabled
Should specify that this controls retention policies for orchestration component indices (Operate, Tasklist, Camunda).
Must clarify that, as implemented, the policy is applied directly on the history (archived) indices, not on index templates.
Suggested Description: If enabled, applies ILM Policy to the archived orchestration indices (operate, tasklist, camunda).

[aabouzaid]

Thanks @houssain-barouni, fixed in #4365