We recently upgraded our builds to use the v4 toolchain, WT-9968. This required editing a lot of places to switch from cmake/toolchains/mongodbtoolchain_v3_clang.cmake to cmake/toolchains/mongodbtoolchain_v4_clang.cmake. We can potentially introduce cmake/toolchains/mongodbtoolchain_stable_clang.cmake that internally includes the latest toolchain. That way in the future we would only need to update that single file.