KAFKA-19767 - Send Share-Fetch one-node at a time for record_limit mode

[ShivsundarR]

What

• After KIP-1206, when record_limit mode was introduced, we ideally
  want no more than the #records in the maxRecords field in
  ShareFetchRequest.

• Currently, the client broadcasts the share fetch requests to all nodes
  which host the leaders of the partitions that it is subscribed to.

• The application thread would be woken up after the first response
  arrives, but meanwhile the responses from other nodes could bring in
  those many #records next and would wait in the buffer, that would mean
  we are wasting the acquisition locks for these records which are
  waiting.

• Instead we would want to only send the next request when we poll
  again.

• PR aims to send the request to only 1 node at a time in record_limit
  mode.

• We are using partition-rotation on each poll so that no partition is
  starved.

There were NCSS checkstyle errors in ShareConsumeRequestManagerTest,
so added a few refactors there to reduce the length.

Performance

• When we have more consumers than the #partitions(i.e when real sharing
  of data happens in a partition), then we are seeing the performance is
  almost the same as the current approach. But when we have lesser
  consumers than the #partitions, then we see a performance regression as
  client is waiting for a node to return a response before it can send the
  next request.
• Hence we have introduced this only for record_limit mode for now,
  future work will be done to improve this area.