External Elasticsearch logging output now supported by Aiven

Aiven now supports sending its service logs to external OpenSearch (or Elasticsearch) services, adding another option to the four available logging options. This integration works by sending log entries as JSON documents to an OpenSearch index with a specified prefix and date format. The fields passed to the new index include HOSTNAME, MESSAGE, SESSION_ID, SYSTEMD_UNIT, and TIMESTAMP. In addition to this latest option, users can access the past two days' logs via Aiven's console, API, or CLI; integrate their logging with one of Aiven's own OpenSearch services for unlimited retention right in Aiven; or use Aiven's syslog integration.