[Feature]: Re-include ElasticSearch as alternative to OpenSearch

### User Story

As a [administrator]
I want to have the possibility of using ElasticSearch as alternative to OpenSearch
So that I have a choice of what to install

### Feature Description

ElasticSearch was removed from DIRAC after moving away from open source, favoring OpenSearch as product of choice. Since a while, ElasticSearch came back as open source, and admins want to have a choice.

Compatibility between the two is anyway not assured, and reported as already diverged. We should understand what can be done and at which cost before proceeding.

### Definition of Done

_No response_

### Alternatives Considered

_No response_

### Related Issues

_No response_

### Additional Context

_No response_