When the container runs with host networking instead of the default bridge, the `$HOSTNAME` / `/etc/hostname` reflects that of the host instead of the container ID , which causes the pytest container to get removed accidentally.
Using a container name instead we can more reliably target the container to avoid removing it, should we need to run with host networking instead.
- Added clarification comment of the DIR command
- Quoted `ARGS` usage required wrapping `ARGS` assignment in an array to properly expand. This wasn't broken before, but is required change to keep ShellCheck lint happy.
- Quote wrapped `DIR` usage, the volume target had an extra `/` before the `DIR` which seems unnecessary as `pwd` should return absolute path.
- Expanded `docker run` options to long-form.
