[WIP] Stateless print by using results from shared filesystem

This removes the stateful print. It gets the resulting file directly from the filesystem. In our case, the filesystem must point to a directory shared by all instances. We have this in the VPC with Zadara.

Only merge/test together with PR in ga3.
Only merge when we are fully in the VPC (this won't work on the classic instances)

When it's merged, we can remove the stateful configuration from our varnishes.