ldap_server: Terminate LDAP connections on krb ticket expiry
See RFC4511 section 4.4.1 and
https://lists.samba.org/archive/cifs-protocol/2020-August/003515.html
for details: Windows terminates LDAP connections when the krb5 ticket
expires, Samba should do the same. This patch slightly deviates from
Windows behaviour by sending a LDAP exop response with msgid 0 that is
ASN1-encoded conforming to RFC4511.
Bug: https://bugzilla.samba.org/show_bug.cgi?id=14465
Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>