*/py-dj52*: Deprecate/Set to expire

• The counterparts of the py-dj52-* ports were switched to Django 5.2 in ce59801b72ef, so the py-dj52-* ports have no more consumers and are now obsolete.

• Set a relatively short EXPIRATION_DATE toward the end of June to wrap up things neatly before the 2026Q3 branch.

PR: 291707
With hat: python