Users in timezones with 30- or 45-minute offsets will no longer see an incorrect timezone mismatch warning when their device and Odoo preferences match. This removes a confusing false alert in user preferences without changing timezone settings behavior.

**Steps to reproduce**
- Set your machine timezone to one ending in :30 or :45
- Open your user preferences and chose the same timezone
Issue: the timezone mismatch icon is displayed.

**Cause**
`.toFixed(0)` rounds to the nearest integer.

**Change**
Always round down the hour part.

opw-5123025

This fix makes a website-related automated test independent from optional demo data. It helps ensure test results are more consistent, reducing false failures in development and release validation.

runbot-162894