[FIX] hr_work_entry_contract: work entry timezone issue for attendance

Steps to reproduce:

- Install Attendances app and Employee app
- Setup an employee with a contract which work entry source is from
attendance
- Change the working schedule to different timezone, for example
Asia/Hong_Kong
- By default the working schedule should be start to work from 0800 to 1700
- Now create an attendance in the first day of the contract, i.e.
1st May 2023, check in time 0700, check out time 2000
- The total work hours should be 13
- However, in the work entry, the genearted work entry is 0800-2000, only
12 work hours.

Current behaviour:
The generated work entry mismatches the value of the attendance

Expected behaviour:
The work entry should match the attendance

Explanation:
This issue is casued by the timezone issue. When the system generate
the work entry, it will calculate the date_from datetime and date_to datetime.
Then it will compare between the attendance and the date_from datetime to choose
the larger datetime to put inside the work entry as start time.

However, the date_from datetime didn't consider the timezone of the working schedule.
In the above example, Asia/Hong Kong time is UTC+8 time. Therefore if we convert
the attendance time back to UTC time. It is check in time 30 April 2023, 2300 to
check out time 1 May 2023, 1200. In the mean time, if we compare between the date_from
datetime (1 May 2023, 0000) and the attendance check in time (30 April 2023, 2300).
The system will take the date_from time and therefore the generated work entry time
is incorrect.

closes odoo/odoo#121233

Related: odoo/enterprise#40976
Signed-off-by: Kevin Baptiste <kba@odoo.com>