The test assume using integraed-as, so make it explicit.
When a toolchain is not using integrated-as, the test would fail because using external assember would increase job counts. Most toolchains in tree use integrated-as, but we still support external assembler. So this is just making it explicit.
Are you planning on adding another patch for the change that you've sent initially? Ideally, I'd like to relax a bit that constraint in Driver.cpp, as in D74447, but that requires first to disable -disable-free to ensure we exit cleanly, at least when runing the tests (a bit like the LLD_IN_TEST env var).