Add an 'CalculateAverages' to XYHistogram test.

This property is not set by default now.

Change-Id: Ie5d7589b9b9b46e9e81b7c3327c4d971392a111f
Merge topic '14931-cluttered-histogram' into next

65ac40d4 Add an 'CalculateAverages' to XYHistogram test.