Bug#1035347: boxer-data: generates dependencies on no longer installable lightning

[Andreas Beckmann]

Followup-For: Bug #1035347
Control: notfixed -1 10.9.4
Control: fixed -1 10.9.6
Control: block 1000872 with -1

The thunderbird-l10n-si change from 10.9.6 needs to be backported to
bullseye as well.


Andreas