[IMP]Timesheet : improve stat button in timesheet to show Number of hour

- Task: https://www.odoo.com/web?debug=#id=9482&view_type=form&model=project.task&menu_id=3942&action=327
- Pad: https://pad.odoo.com/p/r.eHjyjSdhshPhXZNa
Instead of adding a field just to display it twice on the form, maybe you should just remove the first total_timesheet use and use it only in the stat button. Attendance group on the view will be attendance and difference only.