Auto merge of #133747 - lqd:osx-aarch64-1cgu, r=<try>

build `rustc` with 1 CGU on `aarch64-apple-darwin`

Distribute `aarch64-apple-darwin` artifacts built with `rust.codegen-units=1`, like we already do on Linux/Windows/macOS Intel.

1. Performance results (only wall-time on mac as usual)
- I only did some `ripgrep` check builds (the revision from rustc-perf), because we had noticeable wins in wall-time there back then on linux. It's a ~2-4% (mostly 3%) improvement on local builds, and will re-check with CI artifacts once they're available.

2. Effects on code size on `aarch64-apple-darwin`:
- before: TODO, 165MB or so
- after: TODO, 142MB or so

3. Effects on CI
- TODO

r? `@ghost`

try-job: dist-aarch64-apple

Author: bors

src/ci/github-actions/jobs.yml

@@ -338,6 +338,7 @@ auto:
         --set rust.jemalloc
         --set llvm.ninja=false
         --set rust.lto=thin
+        --set rust.codegen-units=1
       RUSTC_RETRY_LINKER_ON_SEGFAULT: 1
       SELECT_XCODE: /Applications/Xcode_15.4.app
       USE_XCODE_CLANG: 1