WIP: Consume SSE events from the backend's StatusUpdater and InfoUpdater

[ulischulte]

Closes #5286

Removed calls to client actuator endpoints in the health and info detail views. Instead, these views now reactively consume the health and info data that are already kept up-to-date via SSE events from the backend's StatusUpdater and InfoUpdater.
Health groups are fetched once per instance (not on every SSE update) and group details are loaded lazily on click. This preserves the #5286 fix (no 1+N requests on SSE status changes) while restoring health group functionality.

[cdprete]

Thanks for the ongoing fix @ulischulte.

Health groups are fetched once per instance (not on every SSE update) and group details are loaded lazily on click.

But aren't the single components in an health group anyway already provided as part of the status update event since it returns the entire health response?
In such a case, I think you can simply the data for the health groups from the status update events and just make sure to merge the needed single statuses under the right group on rendering.