Describe the bug

We currently lack robust end-to-end coverage of our notification system, which includes the backend controllers, cron job scripts, and front-end pages, such as the notifications tab, notifications settings, and email status page.

Expected behavior

A new Cypress file, notifications.spec.js, should be created in the Cypress-Feature workflow to cover all notification release sources, including the cron job script (sbin/send_notification.py). All applicable sources can be found on the notifications page, where we should cover all possible combinations of site/email enable/disabled states.

Additionally, to prevent Cypress code duplication from these sources, existing tests should be updated to use modular Cypress verification methods to share across different testing files.