Zammad 6: Opensearch instead of Elasticsearch - Zammad 6 refuses

[sebix]

FWIW: I have also run the complete Zammad CI test suite against OpenSearch and it succeeded:

docker: set user and password to admin by default

(using GitHub - sebix/zammad at opensearch and GitHub - sebix/zammad-docker-compose at opensearch, no modifications in the code, only in the tests)