[FIX] hr_holidays: fix allocation without validation

In hr_holidays, when the time off type has the following settings:
- Requires allocation: Yes
- Employee Requests: Not allowed
An allocation created with this time off type still requires to be validated.

This commit removes the need to validate an allocation created with the time off type described above.

task-3004313

closes odoo/odoo#106306

X-original-commit: 9377b79cfdcfd088e515fa1a198477bb1dfbc32b
Signed-off-by: Kevin Baptiste <kba@odoo.com>