Describe the bug/error/problem

When iterating through hits using ScrollHelper, an additional search (with scroll) request is made to ElasticSearch for each resulting hit:
https://github.com/elastic/elasticsearch-ruby/blob/main/elasticsearch/lib/elasticsearch/helpers/scroll_helper.rb#L50

This leads to massive latency overhead and makes the ScrollHelper pretty much unusable.

Expected behavior

Additional search (with scroll) requests should be made in only after completing iteration of all current elements in the @docs array, to see if there are more hits to scroll to.