Reminders are configured to trigger a notification after the event instead of before

### What Happened?

When creating a reminder for an event, the time span set to trigger a notification is applied after the event instead of before.

Here's an example of the time set in elementary OS calendar:


This is how Thunderbird reads it:


As well as the Fastmail calendar UI where it is actually hosted:


I've had this issue for ages, and I initially thought it was a timezone mixup. But now I can see it's a bug.

### Steps to Reproduce

1. Create a new event in Calendar
2. Set a reminder for the event (e.g. 2 hours before)
3. Go to another app to see the reminder setting to verify how it's applied

### Expected Behavior

Events should trigger before, just like the Calendar UI communicates it.

### OS Version

7.x (Horus)

### Software Version

Latest release (I have run all updates)

### Log Output

_No response_

### Hardware Info