Fixes #18765 - finish script use FQDN when IP is missing

This is resurrect of

https://github.com/theforeman/foreman/pull/2171/files

The old patch did not pass review because I was unable to explain the
motivation. The reason for the fallback is that only cloud compute
resources usually provide IP addresses but virtualization do not. Our
users often associate finish templates with libvirt or VMWare but it
does not work at all. This only applies to externally managed networks
where we don't know the IP (no reservation made by Foreman).

Now there is a question of safety, with incorrect DNS setup, Foreman
could run finish script on incorrect server. Therefore I am sending this
patch for discussion - I think I could make this behavior an opt-it via
setting.

app/models/concerns/orchestration/ssh_provision.rb

@@ -44,7 +44,7 @@ def delSSHProvisionScript
   end
 
   def setSSHWaitForResponse
-    logger.info "Starting SSH provisioning script - waiting for #{provision_ip} to respond"
+    logger.info "Starting SSH provisioning script - waiting for #{provision_host} to respond"
     if compute_resource.respond_to?(:key_pair) && compute_resource.key_pair.try(:secret)
       credentials = { :key_data => [compute_resource.key_pair.secret] }
     elsif vm.respond_to?(:password) && vm.password.present?
@@ -54,7 +54,7 @@ def setSSHWaitForResponse
     else
       raise ::Foreman::Exception.new(N_('Unable to find proper authentication method'))
     end
-    self.client = Foreman::Provision::SSH.new provision_ip, image.username, { :template => template_file.path, :uuid => uuid }.merge(credentials)
+    self.client = Foreman::Provision::SSH.new provision_host, image.username, { :template => template_file.path, :uuid => uuid }.merge(credentials)
   rescue => e
     failure _("Failed to login via SSH to %{name}: %{e}") % { :name => name, :e => e }, e
   end
@@ -81,7 +81,7 @@ def delSSHCert
   end
 
   def setSSHProvision
-    logger.info "SSH connection established to #{provision_ip} - executing template"
+    logger.info "SSH connection established to #{provision_host} - executing template"
     if client.deploy!
       # since we are in a after_commit callback, we need to fetch our host again, and clean up puppet ca on our own
       Host.find(id).built
@@ -118,7 +118,8 @@ def validate_ssh_provisioning
     failure(_("No finish templates were found for this host, make sure you define at least one in your %s settings") % os) unless status
   end
 
-  def provision_ip
-    provision_interface.ip
+  def provision_host
+    # usually cloud compute resources provide IPs but virtualization do not
+    provision_interface.ip || provision_interface.fqdn
   end
 end