DNS not resolved inside container tool when using --mulled_containers

When starting planemo with with mulled containers support I get that tools which require DNS resolution (because for instance they need to download something) cannot resolve DNS addresses. If I run the same tool container manually through docker run, the container can resolve things fine. In both cases, the injected content on `/etc/resolve.conf` is the same. Maybe this is a wider Galaxy issue if the docker networking is being handled in any particular way by Galaxy

On `docker inspect` on the two cases, tool container sent by Galaxy and container run directly, I can see that the Galaxy one has `"NetworkMode": "none"` where as the working one has `"NetworkMode": "default"`. Is Galaxy on planemo actively setting this somehow?

Start by reproducing the mulled-container case and comparing `docker inspect` output with the working `docker run` case, focusing on `NetworkMode` and `/etc/resolve.conf`. Trace the Planemo/Galaxy container-launch path to determine why the tool receives `NetworkMode: none`; done means the launched tool can resolve DNS as the manual container does.

Written by the indexing model from the issue text.