[ActiveContext] Ensure correct OpenSearch connection params in Indexer

Context

From !198898 (comment 2650021001)

OpenSearch has additional params in gitlab-elasticsearch-indexer, see:

• OpenSearch params: https://gitlab.com/gitlab-org/gitlab-elasticsearch-indexer/-/blob/main/internal/mode/chunk/types/connection.go#L32
• Elasticsearch params: https://gitlab.com/gitlab-org/gitlab-elasticsearch-indexer/-/blob/main/internal/mode/chunk/types/connection.go#L43

And !198898 (comment 2650445843):

OpenSearch has some extra fields. Maybe we could still pass all settings, but the Elasticsearch adapter/client would ignore the extra fields.

References

TBA

Proposal

TBA