gantt: view goes blank with excessive scrolling

[oliver-sanders]

If you zoom in/out using the scroll wheel, the view will eventually go blank.

I think it might happen when all the data has scrolled outside of the bounds of the view?

[ChrisPaulBennett]

Had a good crack at this (#2419) but haven't managed to fix it.
Due to the licensing issue (#2406) we have to move away from apexcharts anyway. Effort will be put into moving away from apex charts instead

[oliver-sanders]

(keeping issue open until the issue is fixed / the chart library replaced)