Fixes #38017 - Update libvirt gems & fix tests

Gems:
* Use fog-libvirt 0.13.0
* Use ruby-libvirt 0.8.3

Tests:
* Use "test:///default" for testing
* Fix failing tests

bundler.d/libvirt.rb

@@ -1,4 +1,4 @@
 group :libvirt do
-  gem 'fog-libvirt', '>= 0.12.0'
+  gem 'fog-libvirt', '>= 0.13.1'
   gem 'ruby-libvirt', '~> 0.5', :require => 'libvirt'
 end

test/controllers/hosts_controller_test.rb

@@ -1218,9 +1218,6 @@ def test_submit_multiple_rebuild_config_pessimistic
   context 'Fog.mock!' do
     setup do
       Fog.mock!
-      Foreman::Model::Libvirt.any_instance.stubs(:hypervisor).returns(stub(:hypervisor))
-      Foreman::Model::Libvirt.any_instance.expects(:max_cpu_count).returns(10)
-      Foreman::Model::Libvirt.any_instance.expects(:max_memory).returns(10000000000)
     end
 
     teardown { Fog.unmock! }

test/unit/compute_resource_host_importer_test.rb

@@ -75,11 +75,11 @@ class ComputeResourceHostImporterTest < ActiveSupport::TestCase
 
   context 'on libvirt' do
     let(:compute_resource) { FactoryBot.build(:libvirt_cr) }
-    let(:uuid) { 'fog-449765558356062' }
+    let(:uuid) { '6695eb01-f6a4-8304-79aa-97f2502e193f' }
 
     test 'imports the VM with all parameters' do
-      assert_equal 'fog-dom1', host.name
-      assert_equal 'dom.uuid', host.uuid
+      assert_equal 'test', host.name
+      assert_equal uuid, host.uuid
       assert_nil host.domain
       assert_equal 'aa:bb:cc:dd:ee:ff', host.mac
       assert_empty host.primary_interface.compute_attributes