[FIX] hr_holidays, resource: use employee time-zone for leave compute

Steps to reproduce:
- Create Allocation for 20 days for Mitchell Admin and validate (12/01 to 12/31).
- Set Working Schedule "Standard 40 hours/week" to UTC timezone.
- Set Mitchell Admin's timezone to Europe/Zurich.
- Create a time off with type Extra Time Off with dates 12/29 - 12/29 and try to save.
- Receive Validation Error: There is no valid allocation to cover that request.

Issues:
You cannot request that leave due to a timezone mismatch, even though you should be able to.

Solution:
To solve the zone mismatch we use the employee timezone to compute the
attendance intervals.

opw-3619178

closes odoo/odoo#146938

Signed-off-by: Bertrand Dossogne (bedo) <bedo@odoo.com>

addons/hr/models/hr_employee.py

@@ -2,7 +2,7 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 import base64
-from pytz import UTC
+from pytz import timezone, UTC
 from datetime import datetime, time
 from random import choice
 from string import digits
@@ -516,7 +516,8 @@ class HrEmployeePrivate(models.Model):
 
     def _get_calendar_attendances(self, date_from, date_to):
         self.ensure_one()
-        return self.resource_calendar_id.get_work_duration_data(date_from, date_to)
+        employee_timezone = timezone(self.tz) if self.tz else None
+        return self.resource_calendar_id.with_context(employee_timezone=employee_timezone).get_work_duration_data(date_from, date_to)
 
     # ---------------------------------------------------------
     # Business Methods

addons/hr_contract/models/hr_employee.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from pytz import UTC
+from pytz import timezone, UTC
 from datetime import date, datetime, time
 
 from odoo import api, fields, models
@@ -145,7 +145,8 @@ class Employee(models.Model):
         valid_contracts = self.sudo()._get_contracts(date_from, date_to, states=['open', 'close'])
         if not valid_contracts:
             return super()._get_calendar_attendances(date_from, date_to)
-        return valid_contracts.resource_calendar_id.get_work_duration_data(date_from, date_to)
+        employee_timezone = timezone(self.tz) if self.tz else None
+        return valid_contracts.resource_calendar_id.with_context(employee_timezone=employee_timezone).get_work_duration_data(date_from, date_to)
 
     def write(self, vals):
         res = super().write(vals)

addons/resource/models/resource_calendar.py

@@ -428,7 +428,7 @@ class ResourceCalendar(models.Model):
         else:
             resources_list = list(resources) + [self.env['resource.resource']]
 
-        attendance_intervals = self._attendance_intervals_batch(start_dt, end_dt, resources, tz=tz)
+        attendance_intervals = self._attendance_intervals_batch(start_dt, end_dt, resources, tz=tz or self.env.context.get("employee_timezone"))
         if compute_leaves:
             leave_intervals = self._leave_intervals_batch(start_dt, end_dt, resources, domain, tz=tz)
             return {