cubicweb #2376625 [ldapfeed] when a user disappears from an ldap source it should be deactivated [validation pending]

and conversely if he re-appears he should be re-activated

priorityimportant
typeenhancement
done in3.15.1
load0.500
load left0.000
closed by#5bee87a14bb1 fix ldap removal handling in ldapfeed (closes #2376625 and #2385133)