Follow-up from "Introduce instrumentation for all Elasticsearch HTTP requests"

The following discussion from !32822 (merged) should be addressed:

• @ashmckenzie started a discussion: (+1 comment)

  thought (non-blocking): If we broke out each service into private methods we could make #add_instrumentation_data a little easier to read and be more SRP focused now that it's on the larger side, e.g.

  def add_instrumentation_data(payload)
    instrument_gitaly(payload)
    ...
  end
  
  private
  
  def instrument_gitaly(payload)
    gitaly_calls = Gitlab::GitalyClient.get_request_count
    return if gitaly_calls.zero?
  
    payload[:gitaly_calls] = gitaly_calls
    payload[:gitaly_duration_s] = Gitlab::GitalyClient.query_time
  end

  Let's leave this as is though 🙂

cc @DylanGriffith