BE: Allow sorting by health status in the issue list

Proposal

Allow sorting by health status in the issue list. This would be useful for users that want to see all issues but review the ones that are not "healthy" first.

The ordering should follow the following behaviour:

• When ascending, healthy issues will be shown first (on track, needs attention, at risk).
• When descending, unhealthy issues will be shown first (at risk, needs attention, on track).
• Issues without a health status will always be shown last.

This issue tracks the backend work only and the frontend work will be completed via #377841 (closed).

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