Clean up supervisor images in the database

[pipex]

On supervisor v18.2.0, we renamed the supervisor service to core in the supervisor
composition. That change also updated the isSupervisor filter in the supervisor-metadata module.

The problem is that when updating to v18.2.0, the following race condition may happen

• The device is on v17.8.5, and the user updates the supervisor on the dashboard to v18.2.0. The target state changes
• Before the update-balena-supervisor script can run, supervisor v17.8.5, sees the new core service which it not part of its filter list and creates the service and image on the database.
• Eventually supervisor v18.2.0 runs, it knows to filter core and tries to remove the image, but its using the image itself, so it gets stuck in a loop trying to remove the image and failing.

This adds a isSupervisor check to the initial application manager image cleanup to avoid the issue happening altogether.

If a customer is stuck in the delete loop, updating to this supervisor should fix it.

Change-type: patch

Release notes

Fixes an issue introduced by the renaming of the supervisor service to core, where the old supervisor could install the core container and image, and the new supervisor would not be able to remove the image due to the image being used by the current supervisor container. This change adds a cleanup step to avoid the image delete loop and restore operation.

[pipex]

How to test

• From a supervisor <18.2.0
• Disable openvpn on the device
• Trigger an update to v18.2.0 or above
• Restart the supervisor to trigger a new poll, wait for the core_xxx container to show up on the engine
• Call update-balena-supervisor you should see the core container get removed and a loop trying to remove the core image
• Update to this supervisor, you should see Device state apply success

[pipex]

This works, I tested two scenarios

• A device on 18.2.0 stuck on the image removal loop, when updated to this version gets to a healthy state
• A device on 17.8.5, updated to this version with the instructions above removes the core container and gets a target state applied