Prevent host-metrics leaking zombie `[timeout]` processes

Fixed

• Fix host-metrics leaking zombie [timeout] processes in Alpine linux containers.

  Before this release AppSignal agent relied on a proper init process that reaps child processes killed by system timeout. Now the agent terminates and reaps unresponsive child processes in host-metrics collection and a subreaper is no longer required.

View the Elixir package v2.17.3 changelog for more information.