fix #2013 spamreport: remove ticket if authmode is ldap

fix #2013 spamreport: remove ticket if authmode is ldap

Currently the 'authmode' setting for the spamquarantine is not used
anywhere. According to documentation setting it to 'ldap' should allow
access to the quarantine only with ldap credentials.

This patch addresses the issue by not generating a quarantineticket,
and adapting all links accordingly if the authmode is 'ldap'.

tested by changing the authmode and running
`pmgqm send -receiver <email-address> -debug 1`

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
Reviewed-By: Dominik Csapak <d.csapak@proxmox.com>
Tested-By: Dominik Csapak <d.csapak@proxmox.com>