Fix for pulp setup

[Shrews]

This fixes the pulp-integration job. Passing results at: https://github.com/Shrews/ansible-builder/actions/runs/4863096603/jobs/8670349109

• Corrects the pulp setup script to run the specified pulp image (it was accidentally running with latest).
• Bumps pulp image to 3.23.3.
• Creates the registries.conf file in setup_pulp.sh now instead of within test_policies.py, while still trying to be considerate of local testing. This was accidentally working because we were running the test_policies.py tests before the test_v3.py tests. But since a previous change switched the order, the test_v3.py tests began failing because we couldn't connect to the pulp registry.
• Remove the image prune and image delete that was happening in test_policies.py test setup. This was only a local testing convenience and doesn't need to happen in CI. As a result, removed the destructive marker.