Following on from the discussion in the WT-11522 PR https://github.com/wiredtiger/wiredtiger/pull/9543#issuecomment-1689043286.

The ubuntu2004-perf-testing and ubuntu2004-arm64-perf-testing were recently created as pinned distros so that the underlying hosts won't change. The primary goal was a consistent baseline for our perf tests, but we've also used this distro for the stress tests under the assumption that stress tests would also benefit from a stable host.

This ticket is to discuss whether the host should be used on stress tests. If we decide no then all non-perf tasks that use this new distro can be reverted back to their original buildvariants. If we decide that they should then we should update the name of the distro to something more generic such as ubuntu2004-stable.