We present an option MONGO_USE_LLD to toggle using -fuse-ld=lld on the build. As of CMake 3.29, this logic is redundant with CMAKE_LINKER_TYPE, which we can rely on going forward.

Since this is just a build-time change, and I doubt any users are relying on it for correct builds, it may be sufficient to just delete the CMake code that handles this logic.