Show average request duration per benchmark set/collector #2344
Description
To help balance the duration of individual benchmark sets, it would be great to see their historical averages. Currently, we only see jobs on the status page when some request is actually in progress, and even then, it's non-trivial to compare the durations of the individual sets.
Ideally, each collector (benchmark set + target combo) on the status page would show a historical average duration for the past e.g. 10 completed requests (not jobs), so that we can compare the durations, and move benchmarks between the benchmark sets to make sure that they stay balanced.