CNG: Use a Linux init process for containers

CNG containers do not use a valid init process. Instead they use they use the main process of the container as PID 1. The side effect of this is that in containers that run processes other than the main process (for example tail or xtail for printing log outputs) this additional processes can become zombie processes.

Using a valid init process such as tini or dumb-init can mitigate this risk and ensure runtime consistency of CNG containers.