LDAP: Return partial results from adminlimit exceeded
    
    Resolves:
        https://fedorahosted.org/sssd/ticket/3185
    
    Since commit c420ce830ac0b0b288a2a887ec2cfce5c748018c we try to move to
    the next server on any error on the connection, which in case there is
    only one server sends SSSD offline.
    
    It's more graceful to try to process the results, same as we already do
    with sizelimit exceeded.
    
    Reviewed-by: Michal Židek <mzidek@redhat.com>
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>