Fix randomly failing tooltip test (#6061)
Fix randomly failing tooltip test (#6061)

Use utility to trigger the event in the center of element rather than x/y -based coordinates (its the edge for rectangles)
touletan/Chart.js,chartjs/Chart.js,touletan/Chart.js,touletan/Chart.js,chartjs/Chart.js,touletan/Chart.js,chartjs/Chart.js,nnnick/Chart.js,chartjs/Chart.js