enrich 'error.exception.type' for captured Elasticsearch client errors for better grouping

# Description

To improve error grouping of captured Elasticsearch client errors, APM agents MAY enrich `error.exception.type` with the "error.type" value from the Elasticsearch response body JSON payload, if easily available.

- spec: https://github.com/elastic/apm/blob/main/specs/agents/tracing-instrumentation-db.md#elasticsearch
- spec PR: https://github.com/elastic/apm/pull/653

The Node.js APM agent implemented this here: https://github.com/elastic/apm-agent-nodejs/issues/2770

## Agent Issues
- [ ] https://github.com/elastic/apm-agent-java/issues/2742
- [ ] https://github.com/elastic/apm-agent-dotnet/issues/1783
- [ ] https://github.com/elastic/apm-agent-python/issues/1611
- [ ] https://github.com/elastic/apm-agent-go/issues/1296
- [ ] https://github.com/elastic/apm-agent-php/issues/744
- [ ] https://github.com/elastic/apm-agent-ruby/issues/1295