Ensure slow logs (index slow logs) are enabled for AWS ElasticSearch Domain

Disabling slow logs may cause loss of insights into performance issues.

In AWS Console -

1. Sign in to the AWS Management Console and go to Amazon ES console.
2. Select the domain you want.
3. Open the Logs tab.
4. Under Set up Search slow logs, choose Setup. You can choose to Create new log group or Use existing log group.

In Terraform -

1. In the aws_elasticsearch_domain resource, create a log_publishing_options block.
2. Set the log_publishing_options.cloudwatch_log_group_arn field to an appropriate CloudWatch ARN ID.
3. Set the log_publishing_options.enabled field to true.
4. Set the log_publishing_options.log_type to INDEX_SLOW_LOGS.

References:
https://docs.aws.amazon.com/opensearch-service/latest/developerguide/createdomain-configure-slow-logs.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/elasticsearch_domain#log_publishing_options