Drop the python3.9 container images (python-builder, python-base,
uwsgi-base). At this point nothing is building off of these images and
we should be using python3.11 for anything new.
Note that python3.10 can be cleaned up once zuul-registry and
openstackclient stop building on top of python3.10. Everything else
appears to be python3.11 at this point.
Change-Id: Id30b616ec336a5599766fb808f55e228da686439