Set ssh_extra_args to ssh_args by default
Set ssh_extra_args to ssh_args by default

Change ssh_extra_args so it defaults to ssh_args. Previous behaviour ignored
default or custom Ansible settings forcing users to duplicate their ssh
settings in multiple places.

The previous setting also leaked some CSC specific config file name
which isn't useful.

CSC-IT-Center-for-Science/ansible-role-users,SoneraCloud/ansible-role-users