[Solved]-Highcharts Gantt Setting Dependency Type-Highcharts

You can manipulate the arrow position by dependency.startMarker.align:

series: [{
    dependency: {
      to: 'prepare_building',
      startMarker: {
        align: 'right',
        color: 'black'
      }
    },
    ...
  }, ...]
}]

Live demo: https://jsfiddle.net/BlackLabel/aycwz7u2/

API Reference: https://api.highcharts.com/gantt/series.gantt.data.dependency.startMarker.align