Make the libvirt ssh_key_file optional in "create-env"

float

@@ -54,7 +54,9 @@ Vagrant.configure(2) do |config|
     libvirt.host = "{{ libvirt.remote_host }}"
     libvirt.username = "{{ libvirt.remote_user }}"
     libvirt.connect_via_ssh = true
+{% if libvirt.ssh_key_file %}
     libvirt.id_ssh_key_file = "{{ libvirt.ssh_key_file }}"
+{% endif %}
 {% endif %}
   end
 
@@ -149,7 +151,6 @@ DEFAULT_VARS = {
     'libvirt': {
         'remote_host': None,
         'remote_user': None,
-        'ssh_key_file': 'id_ed25519',
     },
 
     # Ansible inventory (hosts are created dynamically).