[Test] Mock cookbook virtualenv for Docker tests on AL 2023.

This is required to execute system tests on Docker for AL 2023 that depend on the cookbook virtualenv, siuch as the CloudWatch Agent tests.

Author: gmarciani

cookbooks/aws-parallelcluster-tests/recipes/docker_mock.rb

@@ -74,6 +74,28 @@
   end
 end
 
+if alinux2023_on_docker?
+  # Mock python environment for AL2023 Docker tests
+  # The pyenv/virtualenv setup doesn't work in Docker because it requires S3 access
+  # Create a symlink to system python at the expected cookbook_virtualenv_path
+  python_version = node['cluster']['python-version']
+  virtualenv_path = "#{node['cluster']['system_pyenv_root']}/versions/#{python_version}/envs/cookbook_virtualenv"
+
+  directory "#{virtualenv_path}/bin" do
+    recursive true
+  end
+
+  # Use system python3 as the mock python
+  link "#{virtualenv_path}/bin/python" do
+    to '/usr/bin/python3'
+  end
+
+  bash 'Install cookbook requirements for AL2023' do
+    cwd Chef::Config[:file_cache_path]
+    code "/usr/bin/python3 -m pip install -r cookbooks/aws-parallelcluster-platform/files/cookbook_virtualenv/requirements.txt"
+  end
+end
+
 file '/usr/bin/ssh-keyscan' do
   content %(
     #!/bin/bash