Implement batching series in streaming chunks ingester based on message size.

[pstibrany]

This is similar to #3015, but for chunks-based ingester.

[Jigar3]

I want to work on this issue. It seems that I might require some in-depth knowledge about the ingester to work on this. It would be great if you could help me out by giving some directions on how can I proceed. I will try to read the code of PR #3015 as well, to understand this better.

[jtlisi]

Closing since chunks storage is now in maintenance mode