[ldap] Stop using entities table in ldap source authentication and parser
We may used cwuri for the same purpose, and do one more step towards deletion of
entities.extid column.
Related to #15538288
usr/lib/python2*/*-packages/cubicweb/dataimport/
usr/lib/python2*/*-packages/cubicweb/server/
usr/lib/python2*/*-packages/cubicweb/hooks/
usr/lib/python2*/*-packages/cubicweb/sobjects/
usr/lib/python2*/*-packages/cubicweb/schemas/
usr/share/cubicweb/migration/