group_vars/all was enabling just the sshd jail so move this into the
fail2ban role defaults. patchwork, security and wiki were redefining
fail2ban_jails without deviating from the group_vars/all default and
can therefore be dropped.

These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.

This is meant as a internal authenticated and encrypted network which we
can use for internal services, we don't want to expose to the internet
or when encryption is desired but not easily implementable.