The Elastic Agent fails to update the fleet-server hosts when the first host is unreachable.

Steps to Reproduce:

1. configure fleet-server hosts to have 2 hosts. The first must NOT work, the second should work. (Suggestion, make the first host be https://localhost:8220)
2. I enroll agent by using the working fleet-server URL, the second one
3. the agent successfully installs
4. The agent shows unhealthy on fleet-ui
5. in the agent logs, a error log like the following is found

{"log.level":"error","@timestamp":"2022-09-27T13:38:46.667Z","log.origin":{"file.name":"fleet/fleet_gateway.go","file.line":202},"message":"failed to dispatch actions, error: fail to communicate with updated API client hosts: Get \"https://localhost:8220/api/status?\": dial tcp 127.0.0.1:8220: connect: connection refused","ecs.version":"1.6.0"}

Affected versions

• Version: 8.2.2, 8.6-SNAPSHOT (2b6cfdc)
• Operating System: all
• Discuss Forum URL: N/A