[IMP] db: set default user tz through country code

Given a country code is specified and the country only has one timezone, it is
safe to assume that the admin user is operating from that timezone.

Set the default timezone to simplify the onboarding in such particular case.

If a country has more than one timezone, we can not make safe assumptions and
don't provide a default tz.

closes odoo/odoo#26365

odoo/service/db.py

@@ -10,6 +10,7 @@ import traceback
 from xml.etree import ElementTree as ET
 import zipfile
 
+from pytz import country_timezones
 from functools import wraps
 from contextlib import closing
 from decorator import decorator
@@ -71,6 +72,9 @@ def _initialize_db(id, db_name, demo, lang, user_password, login='admin', countr
             if country_code:
                 country = env['res.country'].search([('code', 'ilike', country_code)])[0]
                 env['res.company'].browse(1).write({'country_id': country_code and country.id, 'currency_id': country_code and country.currency_id.id})
+                if len(country_timezones.get(country_code, [])) == 1:
+                    users = env['res.users'].search([])
+                    users.write({'tz': country_timezones[country_code][0]})
             if phone:
                 env['res.company'].browse(1).write({'phone': phone})
             if '@' in login: