fix: use --no-cache for ansible-galaxy to prevent concurrent cache corruption

When 6 molecule runners install ansible-galaxy collections concurrently,
they share the same response cache, causing:
  Missing expected 'results' in ansible-galaxy cache
  This may indicate cache corruption (from concurrent ansible-galaxy runs)

Adding --no-cache bypasses the shared cache entirely, preventing the
race condition.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

tests/unit/test_setup.py

@@ -108,6 +108,8 @@ class TestInstallAnsibleCollections:
             mock_path.return_value.__str__ = lambda _: str(req)
             _install_ansible_collections(".venv/bin")
         mock_run.assert_called_once()
+        args = mock_run.call_args[0][0]
+        assert "--no-cache" in args, "ansible-galaxy must use --no-cache to avoid concurrent cache corruption"
 
     @patch("devx.tools.setup._run")
     def test_skips_when_no_requirements(self, mock_run: MagicMock) -> None: