As a fix to the issue in #1148 made in #1152. The elastic-agent will no longer report a degraded state if the checkin to fleet-server fails.

This degraded state reporting was used by the liveness endpoint to ensure that the agent reported a 200 status when healthy.
The original changes were added as part of #569.

We need to decide what the liveness endpoint should be reporting and how that interacts with what the agent report to fleet.