[FIX] hr_holidays: Reset interface-based fields on leave type change

Purpose
=======

When changing the leave type on a leave request, reset the technical
fields that only have a visual purpose to avoid mismatch on the leave
duration compute method.

closes odoo/odoo#29789

addons/hr_holidays/models/hr_leave.py

@@ -252,6 +252,12 @@ class HolidaysRequest(models.Model):
         ('duration_check', "CHECK ( number_of_days >= 0 )", "If you want to change the number of days you should use the 'period' mode"),
     ]
 
+    @api.onchange('holiday_status_id')
+    def _onchange_holiday_status_id(self):
+        self.request_unit_half = False
+        self.request_unit_hours = False
+        self.request_unit_custom = False
+
     @api.onchange('request_date_from_period', 'request_hour_from', 'request_hour_to',
                   'request_date_from', 'request_date_to',
                   'employee_id')