Pass --no-self-update to rustup update

Hopefully this will help some of the recent CI issues.

(backport <#4306>)
(cherry picked from commit 8efcf7b)

Author: tgross35

.github/workflows/ci.yaml

@@ -22,7 +22,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Setup Rust toolchain
-        run: ./ci/install-rust.sh
+        run: ./ci/install-rust.sh && rustup component add rustfmt
       - name: Check style
         run: ./ci/style.sh
 

ci/install-rust.sh

@@ -24,7 +24,7 @@ if [ "$os" = "windows" ] && [ -n "${TARGET:-}" ]; then
 fi
 
 rustup set profile minimal
-rustup update --force "$toolchain"
+rustup update --force "$toolchain" --no-self-update
 rustup default "$toolchain"
 
 if [ -n "${TARGET:-}" ]; then

ci/style.sh

@@ -2,12 +2,7 @@
 
 set -eux
 
-if [ -n "${CI:-}" ]; then
-    rustup toolchain install nightly -c rustfmt --allow-downgrade
-    rustup override set nightly
-
-    check="--check"
-fi
+[ -n "${CI:-}" ] && check="--check"
 
 cargo test --manifest-path libc-test/Cargo.toml --test style -- --nocapture