[Elastic Agent] Lazy Acker causes actions queue to grow indefinitely when underlying acker fails

[blakerouse]

Because of the way the Fleet mode of the Elastic Agent is designed it will keep adding the same actions over and over again to the lazy.Acker because the underlying Acker fails to ack the action.

This causes the queue to grow indefinitely that causes the process to consume all the memory of the system.

This is not an issue when Fleet mode can communicate with the Fleet Server, but when it fails the queue just keeps growing until either Fleet Server comes back or the system runs out of memory.

[elasticmachine]

Pinging @elastic/agent (Team:Agent)

[EricDavisX]

should be shipped with 7.15.1 and all coming releases after that