Summary of updates:
- the "sensitive data" checkbox to toggle backup encryption is no longer displayed when a user turns off scheduled backups
- the "Change password" button, which only appears for encrypted backups, is now aligned with the checkbox + description to match the Figma spec
- once scheduled backups are turned off, the latest backup file is deleted via the `BackupService.deleteLastBackup()` method
Tests
- moved browser tests related to the turn-off scheduled backups dialog from `backup_settings.js` to their own file `browser_settings_turn_off_scheduled_backups.js`
- updated some browser tasks testing add/change password to have scheduled backups enabled by default
- added a chrome test for the sensitive data checkbox's visibility whenever scheduled backups are toggled on or off
Depends on https://phabricator.services.mozilla.com/D215543
Differential Revision: https://phabricator.services.mozilla.com/D215826
8573fee2e6