Issue 51222 - It should not be allowed to delete Managed Entry manually
    
    Bug Description: It is possible to delete a managed entry and no error is raised.
    Also, while doing delete or modrdn peration on a managing entry and the managed entry
    doesn't exist, we should continue the operation.
    
    Fix Description: We should put an entry struct duplicate to SLAPI_ENTRY_PRE_OP pblock
    before we execute plugins PRE_OP. Also, we should allow to continue modrdn and delete
    managing entry operations execution even when managed entry doesn't exists.
    Allow 'cn=directory manager' to delete managed entry on direct update.
    
    https://pagure.io/389-ds-base/issue/51222
    
    Reviewed by: ?