Muted hosts continue to generate notification emails

[riversdev0]

Describe the bug
When you mute notifications for a host, notifications are still generated for that host.

Your Environment (please supply the following information):
n/a

Steps To Reproduce

1. You must first have a host that is going to expire soon.
2. Go into the Zone and click the gear icon, and choose "Disable notifications"
3. Next time the expired_certificates cron job runs, you will still receive a notification for that host despite the host being muted.

Screenshots and error logs
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Additional Info
n/a