Fixes #21675 - OpenStack create host tab fails to load

Currently the tab is not loading as there are a few methods that are not
being overridden properly by the FogExtension.

After fixing that and adding the metadata key the tab loads

app/models/compute_resources/foreman/model/openstack.rb

@@ -228,7 +228,7 @@ def volume_client
     end
 
     def vm_instance_defaults
-      super.merge(:key_name => key_pair.name)
+      super.merge(:key_name => key_pair.name, :metadata => {})
     end
 
     def assign_floating_ip(address, vm)

app/models/concerns/fog_extensions/openstack/server.rb

@@ -1,13 +1,9 @@
 module FogExtensions
   module Openstack
     module Server
-      def self.prepended(base)
-        class << base
-          attr_reader :nics
-          attr_accessor :boot_from_volume, :size_gb, :scheduler_hint_filter
-          attr_writer :security_group, :network # floating IP
-        end
-      end
+      attr_reader :nics
+      attr_writer :security_group, :network # floating IP
+      attr_accessor :boot_from_volume, :size_gb, :scheduler_hint_filter
 
       def to_s
         name
@@ -48,11 +44,11 @@ def security_groups
       end
 
       def boot_from_volume
-        attr[:boot_from_volume]
+        attributes[:boot_from_volume]
       end
 
       def size_gb
-        attr[:size_gb]
+        attributes[:size_gb]
       end
 
       def network