Merge branch 'cargo-fmt-faster' into 'master'

Run `cargo fmt` without `--all`

According to [this thread](rust-lang/rustfmt#4247), the `--all` flag causes `cargo-fmt` to call `cargo metadata` for each package in the workspace, which requires a fresh cargo registry locally. However, `cargo fmt --all` is redundant in most cases, as it is in ours. Removing it should speed up the build step. 

See merge request dfinity-lab/public/ic!3054

Author: Jude Taylor

gitlab-ci/src/rust_lint/lint.sh

@@ -2,7 +2,7 @@
 set -xeuo pipefail
 
 cd "$CI_PROJECT_DIR/rs"
-cargo fmt --all -- --check
+cargo fmt -- --check
 cargo clippy --locked --all-features --tests --benches -- -D warnings -D clippy::all -D clippy::mem_forget -C debug-assertions=off
 
 if cargo tree -e features | grep -q 'serde feature "rc"'; then