Use OpenSearch Java client's AwsSdk2Transport

[dlvenable]

Is your feature request related to a problem? Please describe.

The OpenSearch Java client supports an AWS-based transport (AwsSdk2Transport). Investigate using this when sending requests to Amazon OpenSearch Service.

Describe the solution you'd like

Possibly change to use the AWS transport.

Additional context

Suggested by @dblock in #1877 (comment)

[dlvenable]

To solve this, we can update Data Prepper's ConnectionConfiguration provide a method to create an opensearch-java OpenSearchClient object instead of a rest high-level client.

Change the signature of createClient() method to:

OpenSearchClient createClient() {
  ...
}

When SigV4 is enabled, then ConnectionConfiguration::getClient will use the AwsSdk2Transport. Otherwise, continue to create theRestClientTransport.

With this change we should also remove AwsRequestSigningApacheInterceptor.

[dlvenable]

Because the OTelTraceGroupProcessor class uses createClient() it would need to be updated to use opensearch-java as well.