Move heart beat emails to their own service

[andrewleith]

Description

As a notify admin, I need to be able to find system notifications easily in the case of troubleshooting or support.

Now that we send such a large volume of hearbeat notifications, we should consider moving the hearbeat notifications into their own service, so that it is easy to find system notifications in the GC Notify service.

VALUE created by our solution

• Easier administration of Notify

Acceptance Criteria

Given some context, when (X) action occurs, then (Y) outcome is achieved

• [ ] Heartbeat sends are no long listed on the GC notify dashboard
• [ ] Heartbeat sends are now listed in their own service's dashboard

[foudamo]

If someone has capacity, they can pick this card up

[yaelberger-commits]

Hey team! Please add your planning poker estimate with Zenhub @andrewleith @jzbahrai @whabanks

[yaelberger-commits]

Reminder @jzbahrai this card needs estimates from all the devs please

[yaelberger-commits]

Yael will have a convo with @jimleroyer about this one