Silence logging of expected failures

[koetsier]

When indices.get_alias is called with an alias that doesn’t exist, OpenSearch logs the resulting 404 as FATAL.

Use a separate client with logging disabled for this expected failure, so it is handled without adding confusing errors to the application logs.

This issue generates logs when creating indices such as:

 INFO  Services : GET http://opensearch-3:9200/govuk/_alias [status:404, request:0.004s, query:N/A]
FATAL  Services : [404] {"error":{"root_cause":[{"type":"index_not_found_exception","reason":"no such index [govuk]","index":"govuk","resource.id":"govuk","resource.type":"index_or_alias","index_uuid":"_na_"}],"type":"index_not_found_exception","reason":"no such index [govuk]","index":"govuk","resource.id":"govuk","resource.type":"index_or_alias","index_uuid":"_na_"},"status":404}
 INFO  Services : GET http://opensearch-3:9200/ [status:200, request:0.002s, query:n/a]
 INFO  Services : GET http://opensearch-3:9200/_alias/govuk [status:404, request:0.004s, query:N/A]
FATAL  Services : [404] {"error":"alias [govuk] missing","status":404}
 INFO  SearchIndices::IndexGroup : Switching govuk alias from [] to "govuk-2026-09-30t15-10-04z-1d7893c3-d037-4090-aa36-2007f6b91171"
 INFO  Services : POST http://opensearch-3:9200/_aliases [status:200, request:0.019s, query:n/a]
 INFO  Services : GET http://opensearch-3:9200/ [status:200, request:0.002s, query:n/a]
 INFO  Services : PUT http://opensearch-3:9200/page-traffic-2026-09-30t15-10-04z-4bf6ac07-1e5f-4a27-b54c-bec82c41e4c8 [status:200, request:0.092s, query:n/a]
 INFO  SearchIndices::IndexGroup : Created index page-traffic-2026-09-30t15-10-04z-4bf6ac07-1e5f-4a27-b54c-bec82c41e4c8
 INFO  Services : GET http://opensearch-3:9200/ [status:200, request:0.002s, query:n/a]
 INFO  Services : GET http://opensearch-3:9200/page-traffic/_alias [status:404, request:0.002s, query:N/A]
FATAL  Services : [404] {"error":{"root_cause":[{"type":"index_not_found_exception","reason":"no such index [page-traffic]","index":"page-traffic","resource.id":"page-traffic","resource.type":"index_or_alias","index_uuid":"_na_"}],"type":"index_not_found_exception","reason":"no such index [page-traffic]","index":"page-traffic","resource.id":"page-traffic","resource.type":"index_or_alias","index_uuid":"_na_"},"status":404}

The FATAL messages are expected but can confuse and so are best silenced.