[Isolated] Test python pacakges are installed when in an ADC region

Author: hgreebe

cookbooks/aws-parallelcluster-platform/spec/unit/recipes/cookbook_virtualenv_spec.rb

@@ -11,8 +11,10 @@
       context "when cookbook virtualenv not installed yet" do
         cached(:chef_run) do
           runner = runner(platform: platform, version: version) do |node|
+            allow_any_instance_of(String).to receive(:start_with?).with("us-iso").and_return(true)
             node.override['cluster']['system_pyenv_root'] = system_pyenv_root
             node.override['cluster']['python-version'] = python_version
+            node.override['cluster']['region'] = aws_region
           end
           runner.converge(described_recipe)
         end
@@ -34,10 +36,6 @@
           is_expected.to write_node_attributes('dump node attributes')
         end
         context "when in isolated region" do
-          before do
-            allow_any_instance_of(String).to receive(:start_with?).with("us-iso").and_return(true)
-          end
-
           it 'installs python packages' do
             is_expected.to run_bash("pip install").with(
               user: 'root',