mgr/dashboard: Improve workaround to redraw datatables
The current approach to workaround the issue that datatables are not rendered correctly when they are part of a tab and the user switches between those tabs is to fire a 'resize' event to force the datatable to redraw the grid with correct column widths. This approach is like using a sledgehammer to crack a nut. The new approach simply uses Angular's change-detection mechanism. The datatable is marked as changed and Angular will do the rest for us. This should also finally solve the error that variables have been changed after Angular's change-detection has been done.