pv-wrap: Only bind-mount systemd-resolved socket if using a runtime
If we're not using a runtime, then all of /run/systemd is shared between host and container anyway. Mounting a socket over the top of an existing socket fails with "No such device or address" due to a bubblewrap bug (fixed in https://github.com/containers/bubblewrap/pull/409).
This caused the no-runtime
part of the containers.py
test to regress.