[datafeed] Drop entity deletion handling in the default source / parser
This should be handled by specific parser to avoid using "entities.asource".
Reimplement it in the ldap parser.
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/