kvstreamer: improve performance with InOrder mode and random access pattern

This is a continuation of #133043. Using the [same](https://gist.github.com/mgartner/6163ac9079c64ca0d46592ff85f115ce) repro from Marcus, with #134132 included, locally I observe that using the streamer is noticeably slower than disabling it (on average 550ms vs 150ms). We should investigate improving the streamer to handle the scenario with random access (when responses from multiple ranges need to be intertwined) and InOrder mode better.

Jira issue: CRDB-43988