restore IPv6 service on btcpay

in #40836 (closed), we found that HTTPS cert renewals were failing because let's encrypt couldn't reach the server over IPv6. that, in turn was caused by a regression in Docker which was filed as a bug in Debian as well.

the task here is to restore the IPv6 record in LDAP (2604:8800:5000:82:466:38ff:fe07:b154, already configured on the host) once proper behavior is restored. this could be done as part of the %Debian 12 bookworm upgrade or if the docker.io package gets an update to fix the above bug report in bullseye (which I think is rather unlikely).

So for now, just keep this in the bookworm backlog.

Checklist:

• make sure that the docker package is fixed, see https://bugs.debian.org/1017477 for the reproducer
• re-add the AAAA record (2604:8800:5000:82:466:38ff:fe07:b154) in LDAP
• uncomment the record in the reverse zone file (it wasn't commented out)
• monitor (force?) the certificate renewal to make sure that still works