Maximum number of builds to retain in the build history.
When a new build pushes the count over this limit, the oldest entries are removed,
where "oldest" is determined by the build start time recorded in each entry's BuildReportSummary.
Build folders copied in from another machine are subject to the same policy.
A value of 0 disables automatic deletion. Negative values are clamped to 0.
Changes take effect on the next build. The existing history isn't pruned when this value is changed.
This setting is also exposed in Project Settings > Analysis > Build Pipeline.
Additional resources: BuildHistory.ApplyRetentionPolicy