jobs/gerrit: osmo-upf: don't for build debian 10

osmo-upf currently can't build against debian 10, as the required
libnftables-dev version there is too low and we don't provide a backport
for it. As discussed, disable it for debian 10.

Adjust CI to build against debian 11 instead (in addition to the usual
almalinux 8, debian 12).

Change-Id: I63798d451b66bf728b58b02414c1a44f6156b356
1 file changed