Zombienet is a 3rd-party upstream tool — its Docker image should
reference paritytech/zombienet, not pezkuwi/zombienet which doesn't
exist on Docker Hub. This fixes all zombienet test failures caused
by image pull failures.
Docker Hub personal account namespace must match the username.
Updated all docker.io image references across workflows, actions,
docker-compose files, and zombienet configs.
- Fix Docker image tag fallback from 'master' to 'main' to match our default branch
- Bump docker/login-action from v3.5.0 to v3.7.0 for consistency with other workflows
pezkuwichain