alarm reminder is not shown after changing 'reminder within' setting

[forrestguice]

Describe the bug
The alarm reminder notification is not shown for existing alarms after changing the 'reminder within' setting.

To Reproduce

1. Configure the reminder notification to never; Settings -> Alarms -> Reminder within -> never
2. Create an alarm for within the hour.
3. Enable the alarm; no reminder is shown.
4. Configure the reminder to 12 hours; Settings -> Alarms -> Reminder within -> 12 hours
5. Check the notification tray; the reminder still isn't shown.
6. Toggle the alarm disabled, then enabled.
7. Check the notification tray; the reminder is now displayed.

Expected behavior
The reminder should appear for enabled alarms after the "reminder within" setting is changed. Instead the reminder is absent until the alarm is eventually rescheduled.

Version Info:

• App Version: v0.14.11

Additional context
related: #650