[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, such as the CloudWatch Agent tests.

Author: gmarciani

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

@@ -74,6 +74,43 @@
   end
 end
 
+if alinux2023_on_docker?
+  # Install Python 3.12 for AL2023 Docker tests
+  package 'python3.12'
+  package 'python3.12-pip'
+
+  # Mock python environment for AL2023 Docker tests
+  # The pyenv/virtualenv setup doesn't work in Docker because it requires S3 access
+  python_version = node['cluster']['python-version']
+  pyenv_root = node['cluster']['system_pyenv_root']
+  virtualenv_path = "#{pyenv_root}/versions/#{python_version}/envs/cookbook_virtualenv"
+
+  directory "#{virtualenv_path}/bin" do
+    recursive true
+  end
+
+  # Create a wrapper script that reports the expected version but uses system Python
+  file "#{virtualenv_path}/bin/python" do
+    content %(#!/bin/bash
+if [[ "$1" == "-V" || "$1" == "--version" ]]; then
+  echo "Python #{python_version}"
+else
+  exec /usr/bin/python3.12 "$@"
+fi
+)
+    mode '0755'
+  end
+
+  link "#{virtualenv_path}/bin/pip" do
+    to '/usr/bin/pip3.12'
+  end
+
+  bash 'Install cookbook requirements for AL2023' do
+    cwd Chef::Config[:file_cache_path]
+    code "/usr/bin/python3.12 -m pip install -r cookbooks/aws-parallelcluster-platform/files/cookbook_virtualenv/requirements.txt"
+  end
+end
+
 file '/usr/bin/ssh-keyscan' do
   content %(
     #!/bin/bash