We've upgraded to Gerrit 3.11. Once we're comfortable that we are
unlikely to rollback to 3.10 we should drop the image builds and testing
for 3.10. We do this as it is no longer necessary, but also beacuse we
want to rebuild 3.11 on Debian Trixie with Java 21 and don't want to
figure that out for Gerrit 3.10 as well.
A followup to this change will be converting the Gerrit image builds to
Trixie and Java 21, then we can add Gerrit 3.12 images and testing.
Change-Id: I7686e4174a20bfc4076a2f55783f0fc834368c48
0d56571662