Reduce size of RFC 8888 reports

[mengelbart]

In case of packet loss, the interceptor will send repeated reports for the lost packets until the report size is too large. Only when the size gets too large will it advance the range it reports on. In most cases, we don't need to repeat the reports for lost packets because they will never arrive. The reports should instead be contiguous most of the time (see the RFC, too). In some cases, we could add more reports if a delayed packet arrives out of order, but even then, those reports might be ignored by the congestion controller on the other side.