Rollup merge of #139853 - Kobzol:lld-llvm-config, r=onur-ozkan

Disable combining LLD with external llvm-config

When an external `llvm-config` is used, we don't really know anything about the external LLD, as we don't build it ourselves. Therefore, we probably shouldn't allow using `rust-lld` nor copy it to the target sysroot.

Fixes: https://github.com/rust-lang/rust/issues/139477

CC ``@cuviper``

r? ``@onur-ozkan``

try-job: dist-x86_64-linux
try-job: dist-aarch64-linux