[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
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/html/index.html
Files: /usr/share/doc/cubicweb-documentation/html/*