This avoids installing dnf-plugins-core, which breaks the yum and dnf modules
when uninstalling packages using a wildcard after they have already been removed.
This should resolve issues with the yum integration tests failing after docker tests run.
podman 1.4 now installs docker man pages. Add handler to remove docker packages to avoid test failure due to this conflict.
Adjust inventory_docker_swarm integration test
Add conditional to cleanup handlers to allow use of the setup_docker role without removing packages at the end of the play. The inventory_docker_swarm integration tests does its own cleanup.
- use include_vars to set appropriate packages and pip packages per distribution and version
- install an older version of Docker CE on RHEL 8 since a dependency is unavailable
- disable warnings on tasks that are ok
- skip tests for CentOS/RHEL 6
