Capture 'sync' attribute on async spans (part2)

This is a follow-up of #3164

Capture the `span.sync` attribute for the following instrumentation plugins that weren't covered in #3164 :+1:

- [ ] Elasticsearch
- [ ] Finaggle http client
- [ ] gRPC
- [ ] mongodb (3.x and 4.x)
- [ ] process (commons-exec provides an async execution).