A recent upgrade to the ubuntu2004-wt-large distro is causing our compile-clang task to fail. This seems to come from the removal of /usr/bin/clang++ which our compile task is using instead of the mongotoolchain.

We should add the configure_env_vars expansion to all of our buildvariant, ensuring we configure WiredTiger to be compiled with the mongotoolchain in all cases.

This ticket will only add the missing expansion. We'll review correct usage of the mongotoolchain in all cases as part of WT-11230