Instead of writing a legacy network-scripts config file and depending on
the NetworkManager ifcfg-rh plugin.

This will be required on Fedora 35, where NetworkManager's ifcfg-rh
plugin (that parses files in /etc/sysconfig/network-scripts) doesn't
seem to work as it did before.

Hard-coding the ipv6 files for Debian kind of defeats the point of the
network library. However, our network library example42 doesn't provide
any documentation, and no clear examples on how to configure ipv6 for
Debian.

The other alternative, puppet/network, neither provides documentation,
and doesn't even provide any ipv6 examples.

This reverts commit ab786864.

...and other OSs that use the ssh_config.d mechanism.

Use the same name as for the file with the same contents installed by
kickstart on workstations.

...and other OSs that use the ssh_config.d mechanism.

This reverts commit 7fbba434.

Keys in ~/.ssh/authorized_keys still don't work, since sshd is denied
permission when attempting to access that file.

Deleted files/fail2ban/jail_local_ssh-CentOS, files/fail2ban/jail_local_ssh-Debian, files/fail2ban/jail_local_ssh-Fedora, files/fail2ban/jail_local_ssh-Ubuntu files