[ISSUE] Revert Orchestration Cluster service name for backward compatibility

[aabouzaid]

Describe the issue:

In the PR no. #4190 we changed the service name of Orchestration Cluster for consistency, but it actually breaks the upgrade flow from 8.7 to 8.8 as most of the StatefulSet fields are immutable.

The service name is RELEASE-zeebe-headless, where it should be RELEASE-zeebe.

Actions

Revert back to RELEASE-zeebe for the headless service and RELEASE-zeebe-gateway for the stateful service.

[aabouzaid]

FYI: @ChrisKujawa @Langleu