SW: drop bonnie++ from GRML_FULL
bonnie++ is missing from Debian/testing since 2021-10-27, due to
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983999 +
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=999322
Since 2021-08-23 there's a patch available to address the build failure
(see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983999#12), but
sadly there's no progress from upstream / package maintainer since then.
Given that fio exists nowadays, let's see whether there's any need
to include bonnie++ at all.