Container started by Konlet can only use json-file logging driver

Hello,

When Konlet starts a container, logging driver is explicitly set to `json-file` in the code :

https://github.com/GoogleCloudPlatform/konlet/blob/fcc4fb619405c7ec26e8026ab1196a3f043bbf0e/gce-containers-startup/runtime/runtime.go#L311

It will be convenient to be able to change the driver (for example to [`gcplogs`](https://docs.docker.com/config/containers/logging/gcplogs/) if logs have to be redirected to [Google Cloud Logging (Stackdriver)](https://cloud.google.com/logging/docs/)).

Could it be possible to get the logging configuration from `/etc/docker/daemon.json`, or at least to be able to choose the logging driver?

Thank you very much.

Start in gce-containers-startup/runtime/runtime.go at the referenced line around 311, where Konlet sets the Docker logging driver to json-file. Trace how container options are assembled and determine how the requested daemon.json configuration or selectable driver should be represented. Done means Konlet supports a logging driver other than the currently forced json-file setting.

Written by the indexing model from the issue text.