fix: Next alarm showing 'No Upcoming alarm' instead of countdown on iOS device

[oops-shlok]

Description

This PR resolves an issue where the message "No upcoming alarms" was not displayed correctly on iOS devices. Previously, the message was being displayed as "Rings in 23 hours 59 minutes" on iOS, whereas it correctly displayed "No upcoming alarms" on Android devices.

Proposed Changes

• Modified the logic in the refreshUpcomingAlarms() method to ensure that when there are no alarms scheduled, the alarmTime value is set to "No upcoming alarms" for both Android and iOS platforms.
• Tested the modified code on both Android and iOS devices to ensure consistent behavior.

Fixes #480

Screenshots

Checklist

• [ ] Tests have been added or updated to cover the changes
• [ ] Documentation has been updated to reflect the changes
• [x] Code follows the established coding style guidelines
• [ ] All tests are passing

[MarkisDev]

Closing this because this change would reflect on Android as well. Also, it doesn't solve the underlying issue in #480. Feel free to reopen.