Simplify or remove Subversion tests #2097
Description
There are a handful of tests for Subversion that use a very old Debian Bullseye Docker image and an even older Debian Buster viewvc package. These are fragile and recently failed as various old Debian Docker images and repositories were archived. They are likely to cause problems in the future. Whatever these tests are doing with ancient Debian releases and viewvc can likely be simplified so that it works with a generic modern Linux Docker image. If not, then these tests could be deleted entirely, as I doubt we care about Subversion enough to deal with the test instability that it causes.