[VSA] Some median values seem to be incorrect

Problem to solve

Group-level Value Stream Analytics seems to be showing some incorrect median values. For example, for ~"group::analytics" the "Problem Validation" median is currently "1 day". However, only 1 issue had the "problem validation" label applied in the past 30 days, and it was applied 4 days ago. So I would expect the median to be "4 days".

Reproduction instructions

1. Visit Group Level VSA filtered for the group::analytics label
2. Look at the median for the "Problem Validation" stage.
3. Compare that median against what you find in the group::analytics issues with a problem validation label.